JP6305056B2 - Two-dimensional photonic crystal surface emitting laser - Google Patents

Description

  The present invention relates to a two-dimensional photonic crystal surface emitting laser, and more particularly to a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle, beam emission angle, and shape of a laser beam while maintaining stable oscillation. .

  Conventional photonic crystal surface emitting laser diodes (LDs) have used oscillation at the band edge of the Γ point of the photonic band structure.

  In Γ point oscillation, the periodic structure of the photonic crystal has both a function of forming a standing wave for oscillation and a function of diffracting the light in a direction perpendicular to the surface of the photonic crystal layer and extracting the light as an output. (For example, refer to Patent Documents 1 to 3.)

JP 2004-296538 A JP 2000-332351 A JP 2003-23193 A

  The region (oscillation region) of the photonic crystal suitable for the conventional photonic crystal structure with a track record of oscillation is about several hundred μm square, but in this large region, the spread angle is limited to about 1 °, Will become narrower.

  For example, in order to widen the spread angle to 10 °, the oscillation region needs to be about 10 μm or less. In such an oscillation region, it is difficult to realize with the structure of the conventional photonic crystal LD.

  The beam of the photonic crystal surface emitting laser reported so far has a two-dimensionally small shape with a divergence angle of about 1 °. This is a result that arises in principle by taking out the surface perpendicular direction from the two-dimensional large area oscillation.

  On the other hand, depending on the application, a wide beam divergence angle may be desirable. However, the beam divergence angle cannot be controlled with a conventional structure using a square lattice or a triangular lattice.

  The inventors of the present application have theoretically found that it is possible to control the beam divergence angle and shape of the laser beam by the coupler arrangement, and have also proved experimentally.

  The inventors of the present application have theoretically found that the beam divergence angle can be controlled by making the lattice structure of the photonic crystal not a square lattice or a triangular lattice, but a “rectangular lattice”, and experimentally. Also demonstrated.

  In addition, the inventors of the present application have theoretically found and experimentally verified that the beam emission angle and beam divergence angle of the laser beam can be controlled by perturbing the resonance state forming lattice points. .

  An object of the present invention is to provide a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle and shape of a laser beam while maintaining stable oscillation by the coupler arrangement.

  It is another object of the present invention to provide a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle while maintaining stable oscillation with a simple structure using a rectangular lattice.

  Another object of the present invention is to control the beam emission angle, beam divergence angle, and shape of the laser beam while maintaining stable oscillation with a simple structure by adding perturbations to the resonance state forming lattice points. The object is to provide a two-dimensional photonic crystal surface emitting laser.

According to one aspect of the present invention, a photonic crystal layer and a light wave that is periodically disposed in the photonic crystal layer and at the band edge of the photonic band structure of the photonic crystal layer are converted into the photonic crystal layer. A resonance state forming lattice point that is diffracted in the plane of the light, and the perturbation for diffracting the light wave in a direction perpendicular to the plane of the photonic crystal layer is applied to the resonance state forming lattice point, A two-dimensional photonic crystal surface emitting laser in which a plurality of perturbations are applied to the resonance state forming lattice point is provided.

According to another aspect of the present invention, a photonic crystal layer and a light wave periodically disposed in the photonic crystal layer, the light wave at the band edge of the photonic band structure of the photonic crystal layer, Resonant state forming lattice points that are diffracted in the plane of the layer and light waves at the band edges of the photonic band structure of the photonic crystal layer that are periodically disposed in the photonic crystal layer, the photonic crystal layer And a perturbation state forming lattice point that diffracts in the plane of the photonic crystal layer and diffracts in a direction perpendicular to the surface of the photonic crystal layer. formed perturbation for diffracting direction is applied to a portion of the resonating lattice points, wherein the perturbed state forming grid points, the plurality of perturbation is added 2-dimensional photonic crystal surface-emitting laser have is provided.

According to another aspect of the present invention, a photonic crystal layer and a light wave disposed within the photonic crystal layer and disposed at the X-point band edge in the photonic band structure of the photonic crystal layer are converted into the photonic crystal layer. A resonant state forming lattice point of a rectangular lattice that is diffracted in the plane of the substrate and diffracted in a direction perpendicular to the surface, and the light wave is transmitted to the resonant state forming lattice point in a direction perpendicular to the surface of the photonic crystal layer. And a lattice constant of the rectangular lattice is a ₁ and a ₂ , a two-dimensional photonic crystal in which one side a ₂ of the rectangular lattice is equal to ½ of the wavelength in the medium A surface emitting laser is provided.

According to another aspect of the present invention, a photonic crystal layer and a light wave disposed within the photonic crystal layer and disposed at the X-point band edge in the photonic band structure of the photonic crystal layer are converted into the photonic crystal layer. A perturbation that diffracts a light wave at a resonance point forming lattice point of a rectangular lattice to be diffracted in the plane and an X point band edge in the photonic band structure of the photonic crystal layer in a direction perpendicular to the plane of the photonic crystal layer A state forming lattice point, wherein the perturbation state forming lattice point adds a perturbation for diffracting the light wave in a direction perpendicular to the plane of the photonic crystal layer to a part of the resonance state forming lattice point. It is formed, and the lattice constant of the rectangular lattice and a ₁ and a _2, 2-dimensional photonic equal side a ₂ of said rectangular lattice is 1/2 of the wavelength in the medium Planes emitting laser is provided.

According to another aspect of the present invention, a photonic crystal layer and a light wave disposed within the photonic crystal layer and disposed at the X-point band edge in the photonic band structure of the photonic crystal layer are converted into the photonic crystal layer. The light wave at the resonance point forming lattice point of the first rectangular lattice to be diffracted in the plane and the X point band edge in the photonic band structure of the photonic crystal layer in the direction perpendicular to the plane of the photonic crystal layer A perturbation state forming lattice point to be diffracted, wherein the perturbation state forming lattice point has a perturbation for diffracting the light wave in a direction perpendicular to the plane of the photonic crystal layer. The perturbation state forming lattice points are arranged in a second rectangular lattice different from the first rectangular lattice, and are arranged in the x direction of the second rectangular lattice. The lattice constant of fine y-direction, the first with respect to the x and y directions of the lattice constants a ₁ and a ₂ of the rectangular lattice, the two-dimensional photo is equal to a ₁ and medium wavelength lambda (= 2a ₂₎ A nick crystal surface emitting laser is provided.

According to another aspect of the present invention, a photonic crystal layer and a light wave disposed within the photonic crystal layer and disposed at the X-point band edge in the photonic band structure of the photonic crystal layer are converted into the photonic crystal layer. A perturbation state that diffracts a light wave at a resonance point forming lattice point of a rhomboid lattice to be diffracted in the plane and an X point band end in the photonic band structure of the photonic crystal layer in a direction perpendicular to the plane of the photonic crystal layer The perturbation state formation lattice point is configured such that a perturbation for diffracting the light wave in a direction perpendicular to the plane of the photonic crystal layer is added to a part of the resonance state formation lattice point. The perturbation state forming lattice points are arranged in a rectangular lattice, and the lattice constant of the rectangular lattice is equal to the lattice constants a ₁ and a _{2 of the} rhomboid lattice. Thus, a two-dimensional photonic crystal surface emitting laser equal to a ₁ and the in-medium wavelength λ is provided.

  According to the present invention, it is possible to provide a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle and shape of the laser beam while maintaining stable oscillation by the coupler arrangement.

  Further, according to the present invention, it is possible to provide a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle while maintaining stable oscillation with a simple structure using a rectangular lattice.

  In addition, according to the present invention, by controlling the lattice point for forming the resonance state, it is possible to control the beam emission angle, beam divergence angle, and shape of the laser beam while maintaining stable oscillation with a simple structure. A two-dimensional photonic crystal surface emitting laser can be provided.

FIG. 2 is a schematic bird's-eye view of the two-dimensional photonic crystal surface emitting laser according to the first embodiment. The band structure figure of the two-dimensional photonic crystal applied to the two-dimensional photonic crystal surface emitting laser concerning a 1st embodiment. In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) a schematic explanatory view of an in-plane resonance mode of the two-dimensional photonic crystal layer, (b) an emitted surface emitting laser beam hν _L And FIG. 7C is a schematic diagram of the laser light hν _{R in} the resonator, and (c) a schematic diagram of the surface emitting laser light hν _L emitted from the two-dimensional photonic crystal layer including the coupler lattice point 12C. In the two-dimensional photonic crystal surface emitting laser which concerns on a comparative example, the typical plane block diagram of the lattice point for resonators of the two-dimensional photonic crystal layer applied to (GAMMA) point oscillation (square lattice arrangement example). In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) a schematic plan configuration diagram of resonator lattice points and coupler lattice points of a two-dimensional photonic crystal layer applied to M-point oscillation (Example of square lattice arrangement), (b) Band structure diagram of a two-dimensional photonic crystal corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, an enlarged schematic plan configuration diagram of resonator lattice points and coupler lattice points of a two-dimensional photonic crystal layer applied to M-point oscillation (Example of square lattice arrangement). (A) The typical cross-section figure along the II-II line of FIG. 6, (b) The typical cross-section figure along the III-III line of FIG. FIG. 6 is a schematic cross-sectional structure diagram of the two-dimensional photonic crystal surface emitting laser according to the first embodiment along the line II in FIG. 5. (A) Schematic cross-sectional structure diagram of a two-dimensional photonic crystal surface emitting laser according to Modification 1 of the first embodiment along the II line in FIG. 5, (b) In the II line in FIG. The typical cross-section figure of the two-dimensional photonic crystal surface emitting laser which concerns on the modification 2 of 1st Embodiment which follows. (A) A schematic cross-sectional structure diagram of a two-dimensional photonic crystal surface emitting laser according to Modification 3 of the first embodiment along the line I-I in FIG. 5; The typical cross-section figure of the two-dimensional photonic crystal surface emitting laser which concerns on the modification 4 of 1st Embodiment which follows. In the two-dimensional photonic crystal surface-emitting laser according to the first embodiment, the width A of the coupler region CP, a diagram showing the relationship between beam divergence angle and beam spread region, the (a) coupler regions CP ₁ examples of width a _1, the beam divergence angle theta _1, and the beam divergence region 30 _1, (b) examples of couplers width a ₂ of the area CP _2, the beam divergence angle theta _2, and the beam divergence region 30 _2, (c) a coupler examples of region width a ₃ of CP _3, beam spread angle theta _3, and beam spread region 30 _3. In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) the size relationship of the resonator region RP corresponding to FIGS. 11 (a), 11 (b), and 11 (c) is shown. FIG. 12B is a diagram showing the magnitude relationship of the beam divergence angle θ ₀ corresponding to FIG. 11A, FIG. 11B, and FIG. In the two-dimensional photonic crystal surface emitting laser according to the comparative example, it is a diagram showing the relationship of the size of the resonator region RP of the two-dimensional photonic crystal layer applied to the Γ-point oscillation, and (a) RP ₁ Examples, (b) RP ₂ example, (c) RP ₃ example. FIG. 3 is a diagram showing the relationship between the size of a resonator region RP and a coupler region CP of a two-dimensional photonic crystal layer applied to M-point oscillation in the two-dimensional photonic crystal surface emitting laser according to the first embodiment. (A) Examples of RP ₁ and CP ₁ (b) Examples of RP ₂ and CP ₂ (c) Examples of RP ₃ and CP ₃ In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the resonator lattice point 12A in the resonator region RP and the coupler region CP of the two-dimensional photonic crystal layer applied to the M point oscillation is used for the coupler. An arrangement example of the lattice point 12C. In the two-dimensional photonic crystal surface-emitting laser according to the first embodiment, (a) example of the light-emitting photonic crystal layer 12 ₂ a coupler for grid point 12C disposed, (b) Photo for the standing wave formed example in which the resonator grid point 12A to the photonic crystal layer _121, an example of arranging the resonator grid points 12A and couplers lattice point 12C on the same photonic crystal layer 12 (c), (d) the same photonic Another example in which the resonator lattice point 12A and the coupler lattice point 12C are arranged in the crystal layer 12, (e) Still another example in which the resonator lattice point 12A and the coupler lattice point 12C are arranged in the same photonic crystal layer 12. Example. In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) when the sizes of the resonator region RP and the coupler region CP of the two-dimensional photonic crystal layer applied to the M point oscillation are substantially equal. (NFP: Near Field Pattern), (b) Schematic diagram showing a beam expansion region from the coupler region CP, (c) Resonance in the resonator region RP and the coupler region CP corresponding to FIG. The example of arrangement | positioning of the lattice point for dexterity and the lattice point for couplers. In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) when the sizes of the resonator region RP and the coupler region CP of the two-dimensional photonic crystal layer applied to the M point oscillation are different. NFP, (b) Schematic diagram showing a beam expansion region from the coupler region CP, (c) Resonator region RP corresponding to FIG. 18 (a), arrangement of resonator lattice points and coupler lattice points in the coupler region CP Example. In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) a relatively large circular coupler region CP in the resonator region RP of the two-dimensional photonic crystal layer applied to M-point oscillation. (B) A far field image (FFP: Farr Field Pattern) corresponding to FIG. 19 (a). In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) NFP with a relatively small circular coupler region CP in the resonator region RP, (b) FIG. 20 (a). FFP corresponding to. In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) a relatively small circular coupler region in the resonator region RP of the two-dimensional photonic crystal layer applied to M-point oscillation NFP with CP, (b) FFP corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) a relatively large oval coupler region in the resonator region RP of the two-dimensional photonic crystal layer applied to M-point oscillation NFP with CP, (b) FFP corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) a relatively small circular coupler region CP in the resonator region RP of the two-dimensional photonic crystal layer applied to M-point oscillation. (B) FFP corresponding to FIG. 23 (a). In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) two oval shapes orthogonal to each other in the resonator region RP of the two-dimensional photonic crystal layer applied to the M point oscillation NFP with coupler region CP, (b) FFP corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) three resonators crossing each other at 60 degrees in the resonator region RP of the two-dimensional photonic crystal layer applied to the M point oscillation NFP with oval coupler region CP, (b) FFP corresponding to FIG. In the two-dimensional photonic crystal surface-emitting laser according to the first embodiment, (a) two pieces intersecting each other at 120 degrees in the resonator region RP of the two-dimensional photonic crystal layer applied to the M point oscillation NFP with oval coupler region CP, (b) FFP corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, (a) five resonators crossing each other at 72 degrees in the resonator region RP of the two-dimensional photonic crystal layer applied to the M point oscillation NFP with oval coupler region CP, (b) FFP corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the second embodiment, (a) a schematic plan configuration diagram of resonator lattice points and coupler lattice points of a two-dimensional photonic crystal layer applied to X-point oscillation (Example of square lattice arrangement), (b) Band structure diagram of a two-dimensional photonic crystal corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the third embodiment, (a) a schematic plan configuration diagram of resonator lattice points and coupler lattice points of a two-dimensional photonic crystal layer applied to X-point oscillation (Triangular lattice arrangement example), (b) Band structure diagram of a two-dimensional photonic crystal corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the fourth embodiment, (a) a schematic plan configuration diagram of resonator lattice points and coupler lattice points of a two-dimensional photonic crystal layer applied to J-point oscillation (Triangular lattice arrangement example), (b) Band structure diagram of a two-dimensional photonic crystal corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the fifth embodiment, (a) a schematic plan configuration diagram of resonator lattice points and coupler lattice points of a two-dimensional photonic crystal layer applied to X-point oscillation (Example of arrangement of rectangular lattices), (b) Band structure diagram of a two-dimensional photonic crystal corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the sixth embodiment, (a) a schematic plan configuration diagram of resonator lattice points and coupler lattice points of a two-dimensional photonic crystal layer applied to X-point oscillation (Rhombus lattice arrangement example), (b) Band structure diagram of a two-dimensional photonic crystal corresponding to FIG. An example of arrangement when the diameter D _r of the resonator lattice point 12A and the diameter D _c of the coupler lattice point 12C are different, and (a) an example of arrangement at the same point with D _c ≦ D _r , (b) An example in which D _c > D _r is arranged at the same point. It is an arrangement example when the shape of the resonator lattice point 12A and the shape of the coupler lattice point 12C are different, and (a) the resonator lattice point 12A has a circular shape, and the coupler lattice point 12C has a triangular shape. ) An example in which the resonator lattice point 12A has a rhombus shape and the coupler lattice point 12C has an elliptical shape. FIG. 10 is a schematic bird's-eye view of a two-dimensional photonic crystal surface emitting laser according to a seventh embodiment. An example of a far field pattern (FFP: Far Field Pattern) emitted from a two-dimensional photonic crystal surface emitting laser according to a seventh embodiment. In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, (a) a schematic explanatory view of an in-plane resonance mode of the two-dimensional photonic crystal layer, (b) an emitted surface emitting laser beam hν _L And a schematic diagram of the laser beam hν _{R in} the resonator. In the two-dimensional photonic crystal surface emitting laser which concerns on 7th Embodiment, the schematic plane block diagram of the lattice point for resonators of the two-dimensional photonic crystal layer applied to (GAMMA) point oscillation (rectangular lattice arrangement example). (A) Typical cross-section diagram along line IV-IV in FIG. 38, (b) Typical cross-section diagram along line VV in FIG. The two-dimensional photonic crystal surface emitting laser according to the seventh embodiment has a band structure in the case of an aspect ratio r = 1.015 in rectangular lattice Γ-point oscillation, and has a normalized frequency (c / a) and The figure which shows the relationship with a wave number. The two-dimensional photonic crystal surface emitting laser according to the seventh embodiment has a band structure when the aspect ratio r = 1.03 in rectangular lattice Γ-point oscillation, and has a normalized frequency (c / a) and The figure which shows the relationship with a wave number. The two-dimensional photonic crystal surface emitting laser according to the seventh embodiment has a band structure when the aspect ratio r = 1.045 in rectangular lattice Γ-point oscillation, and has a normalized frequency (c / a) and The figure which shows the relationship with a wave number. In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, the real space of the lattice points of the resonator rectangular lattice. In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, the wave number space of a resonator rectangular lattice. The FFP measurement experiment result in the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment when the aspect ratio r = 1.015 in rectangular lattice Γ point oscillation. The FFP measurement experiment result in the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment when the aspect ratio r = 1.03 in rectangular lattice Γ point oscillation. The FFP measurement experiment result when the aspect ratio r = 1.045 in the rectangular lattice Γ-point oscillation in the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment. (A) Schematic sectional view of a two-dimensional photonic crystal surface emitting laser according to the seventh embodiment taken along line IV-IV in FIG. 38, (b) A seventh taken along line VV in FIG. The typical cross-section figure of the two-dimensional photonic crystal surface emitting laser which concerns on embodiment. (A) Schematic cross-sectional structure diagram of a two-dimensional photonic crystal surface emitting laser according to a modification of the seventh embodiment along the IV-IV line in FIG. 38, (b) along the VV line in FIG. The typical cross-section figure of the two-dimensional photonic crystal surface emitting laser which concerns on the modification of 7th Embodiment. In the two-dimensional photonic crystal surface emitting laser which concerns on 8th Embodiment, it is a band structure in rectangular lattice X point oscillation, Comprising: The figure which shows the relationship between the normalized frequency (c / a) and a wave number. In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, a real space of lattice points of a resonator rectangular lattice. In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, a wave number space of a resonator rectangular lattice. In the two-dimensional photonic crystal surface emitting laser which concerns on 8th Embodiment, the typical plane block diagram of the lattice point for resonators of the two-dimensional photonic crystal layer applied to X point oscillation (rectangular lattice arrangement example). Schematic plan configuration diagram of resonator lattice points and coupler lattice points of a two-dimensional photonic crystal layer applied to X-point oscillation in a two-dimensional photonic crystal surface emitting laser according to an eighth embodiment Example of lattice arrangement). 54A is a schematic cross-sectional structure diagram taken along the line VI-VI in FIG. 54, and FIG. 54B is a schematic cross-sectional structure diagram along the line VII-VII in FIG. 54. (A) A schematic sectional view of a two-dimensional photonic crystal surface emitting laser according to the eighth embodiment along the VI-VI line in FIG. 54, (b) an eighth along the VII-VII line in FIG. The typical cross-section figure of the two-dimensional photonic crystal surface emitting laser which concerns on embodiment. (A) Schematic sectional view of a two-dimensional photonic crystal surface emitting laser according to Modification 1 of the eighth embodiment along the VI-VI line in FIG. 54, (b) along the VII-VII line in FIG. The typical cross-section figure of the two-dimensional photonic crystal surface emitting laser which concerns on the modification 1 of 8th Embodiment which follows. (A) A schematic cross-sectional structure diagram of a two-dimensional photonic crystal surface emitting laser according to Modification 2 of the eighth embodiment along the VI-VI line of FIG. 54, (b) a VI-VI line of FIG. FIG. 5C is a schematic cross-sectional structure diagram of a two-dimensional photonic crystal surface emitting laser according to Modification 3 of the eighth embodiment, FIG. 54 is a fourth modification of the eighth embodiment along the line VI-VI in FIG. The typical cross-section figure of the two-dimensional photonic crystal surface emitting laser which concerns on. In the two-dimensional photonic crystal surface emitting laser according to the fifth modification of the eighth embodiment, (a) a schematic diagram of resonator lattice points and coupler lattice points of a two-dimensional photonic crystal layer applied to X-point oscillation FIG. 5B is a band structure of a two-dimensional photonic crystal corresponding to FIG. 59A, and shows the relationship between the normalized frequency (c / a) and the wave number. . In the two-dimensional photonic crystal surface emitting laser according to Modification 6 of the eighth embodiment, (a) a schematic diagram of resonator lattice points and coupler lattice points of a two-dimensional photonic crystal layer applied to X-point oscillation FIG. 60 is a schematic plan configuration diagram (diamond lattice arrangement example), (b) a band structure diagram of a two-dimensional photonic crystal corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, resonator lattice points 12A and couplers in the resonator region RP and coupler region CP of the two-dimensional photonic crystal layer applied to the X-point oscillation are used. An arrangement example of the lattice point 12C. In the two-dimensional photonic crystal surface-emitting laser according to an embodiment of the 8, (a) example of the light-emitting photonic crystal layer 12 ₂ a coupler for grid point 12C disposed, (b) Photo for the standing wave formed example in which the resonator grid point 12A to the photonic crystal layer _121, an example of arranging the resonator grid points 12A and couplers lattice point 12C on the same photonic crystal layer 12 (c), (d) the same photonic Another example in which the resonator lattice point 12A and the coupler lattice point 12C are arranged in the crystal layer 12, (e) Still another example in which the resonator lattice point 12A and the coupler lattice point 12C are arranged in the same photonic crystal layer 12. Example, (f) Still another example in which resonator lattice points 12A and coupler lattice points 12C are arranged on the same photonic crystal layer 12. In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, (a) the size of the resonator region RP and the coupler region CP of the two-dimensional photonic crystal layer applied to the X point oscillation are substantially equal (NFP: Near Field Pattern), (b) Schematic diagram showing a beam expansion region from the coupler region CP, (c) Resonance in the resonator region RP and the coupler region CP corresponding to FIG. 63 (a) The example of arrangement | positioning of the lattice point for dexterity and the lattice point for couplers. In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, (a) when the sizes of the resonator region RP and the coupler region CP of the two-dimensional photonic crystal layer applied to the X-point oscillation are different NFP, (b) Schematic diagram showing a beam expansion region from the coupler region CP, (c) Resonator region RP corresponding to FIG. 64 (a), resonator lattice point 12A and coupler lattice point 12C in the coupler region CP Example of arrangement. In the two-dimensional photonic crystal surface-emitting laser according to the eighth embodiment, the diameter D of the diameter D _r and couplers lattice point 12C of the resonator grid points 12A of the two-dimensional photonic crystal layer applied to the X point oscillation An example of arrangement when _c is different, (a) an example arranged at the same point with D _c ≦ D _r , and (b) an example arranged at the same point with D _c > D _r . In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, when the shape of the resonator lattice point 12A and the shape of the coupler lattice point 12C of the two-dimensional photonic crystal layer applied to the X-point oscillation are different (A) An example in which the shape of the resonator lattice point 12A is a circle and the coupler lattice point 12C is a triangle, and (b) a shape of the resonator lattice point 12A is a rhombus, and the coupler lattice point 12C is an ellipse. Example of shape. The typical bird's-eye view structure figure of the two-dimensional photonic crystal surface emitting laser which concerns on 9th Embodiment. (A) Real space of a rectangular lattice of a two-dimensional photonic crystal layer applied to the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, (b) a wave number space corresponding to FIG. 68 (a) . FIG. 5 is a diagram illustrating the principle of surface emission of a two-dimensional photonic crystal surface emitting laser, in which a two-dimensional photonic crystal layer has lattice points of a rectangular lattice, and (a) the length of a two-dimensional photonic crystal layer. Explanatory drawing in the real space of the in-plane resonance state of a square lattice, (b) Explanatory drawing in the wave number space corresponding to Fig.69 (a). (A) in-plane resonance state corresponding to FIG. 69, illustrating the wave number space k _x -k _y diffraction operation in the upward direction (z-axis direction), the wave number corresponding to (b) Figure 70 (a) space illustration in the k _z -k _y. In the two-dimensional photonic crystal surface emitting laser according to the comparative example, (a) an example of arrangement in real space of the lattice points (square lattice) for forming the resonance state of the two-dimensional photonic crystal layer, (b) the two-dimensional photonic crystal layer Example of real space arrangement of light extraction lattice points, (c) Real space arrangement example combining resonance state forming lattice points and light extraction lattice points, (d) Wave number space corresponding to FIG. 71 (a), (e ) Wave number space corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, (a) an example of arrangement in real space of lattice points (rectangular lattice) for forming a resonance state of the two-dimensional photonic crystal layer, (b) two-dimensional Conceptual diagram for explaining how a perturbation of a sinusoidal function is applied to the lattice point (rectangular lattice) for forming a resonance state of the photonic crystal layer in the y-axis direction, (c) a lattice for forming the resonance state of the two-dimensional photonic crystal layer The conceptual diagram explaining a mode that the perturbation of hole shape (hole diameter) modulation | alteration is added to a point (rectangular lattice) in the y-axis direction. (A) Wave number space corresponding to FIG. 72 (a), (b) Wave number space corresponding to FIG. 72 (b). In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a real space for explaining a state in which a perturbation of refractive index modulation is applied to a lattice point (rectangular lattice) for forming a resonance state of a two-dimensional photonic crystal layer Arrangement example. Explained in the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment is the perturbation of the hole shape (hole diameter) modulation applied to the resonance state forming lattice points (rectangular lattice) of the two-dimensional photonic crystal layer. Example of real space layout. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a state in which perturbation of hole depth modulation is applied to a resonance state forming lattice point (rectangular lattice) of the two-dimensional photonic crystal layer will be described. Real space layout example. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, the hole shape (hole diameter) is modulated in the y-axis direction at the resonance state forming lattice point (rectangular lattice X point) of the two-dimensional photonic crystal layer. Real space layout example with perturbation. The wave number space corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, the hole shape (hole diameter) is modulated in the y-axis direction at the resonance state forming lattice point (rectangular lattice X point) of the two-dimensional photonic crystal layer. Numerical examples of lattice constants (a _x , a _y ), hole diameter d ₁ , perturbation _factor s (= a _y / a _yc ), and beam emission angle θ when perturbation is applied. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, the hole shape (hole diameter) is modulated in the y-axis direction at the resonance state forming lattice point (rectangular lattice X point) of the two-dimensional photonic crystal layer. It is an experimental result at the time of adding a perturbation, Comprising: (a) Far-field image (FFP: Far Field Pattern) and beam emission angle (theta) at the time of perturbation system number s = 0.96, (b) Perturbation system number s = 0. FFP and beam emission angle θ when 98, (c) FFP and beam emission angle θ when perturbation system number s = 0.98, 0.96. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, perturbation of the hole shape (hole diameter) modulation in the y-axis direction is applied to the resonance state forming lattice point (rectangular lattice) of the two-dimensional photonic crystal layer. Real space layout example when added. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, the hole shape (hole diameter) modulation is performed in the y-axis direction on the resonance state forming lattice point (face-centered rectangular lattice) of the two-dimensional photonic crystal layer. An example of real space arrangement when perturbation is added. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a perturbation of hole shape (hole diameter) modulation is applied to the lattice point (square lattice) for forming a resonance state of the two-dimensional photonic crystal layer in the y-axis direction. An example of real space layout. FIG. 6 is a schematic explanatory diagram of an FFP at a resonance state forming lattice point (square lattice Γ point) of a two-dimensional photonic crystal layer in a two-dimensional photonic crystal surface emitting laser according to a comparative example. FIG. 6 is a schematic explanatory diagram of an FFP at a resonance state forming lattice point (rectangular lattice Γ point) of a two-dimensional photonic crystal layer in a two-dimensional photonic crystal surface emitting laser according to a comparative example. In the two-dimensional photonic crystal surface emitting laser according to the comparative example, a schematic explanatory diagram of the FFP in the case where the light extraction lattice point is superimposed on the resonance state forming lattice point (square lattice M point) of the two-dimensional photonic crystal layer . In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, the hole shape (hole diameter) is modulated in the y-axis direction at the resonance state forming lattice point (rectangular lattice X point) of the two-dimensional photonic crystal layer. The typical explanatory view of FFP at the time of adding perturbation. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a perturbation of hole depth modulation is applied to the lattice point (rectangular lattice) for forming the resonance state of the two-dimensional photonic crystal layer in the y-axis direction. The typical planar pattern block diagram of the lattice point 12P for perturbation state formation. (A) Schematic cross-sectional structure diagram along line VIII-VIII in FIG. 88, (b) Schematic cross-sectional structure diagram along line IX-IX in FIG. 88, (c) Schematic diagram along line XX in FIG. FIG. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a perturbation in which a perturbation of refractive index modulation is added in the y-axis direction to a resonance state forming lattice point (rectangular lattice) of the two-dimensional photonic crystal layer The typical plane pattern block diagram of the grid point 12P for state formation. (A) Example of refractive index distribution in x-axis direction along line XI-XI in FIG. 90, (b) Example of refractive index distribution in x-axis direction along line XII-XII in FIG. 90, (c) XIII- in FIG. An example of the refractive index distribution in the x-axis direction along the XIII line. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, perturbation of the hole shape (hole diameter) modulation in the y-axis direction is applied to the resonance state forming lattice point (rectangular lattice) of the two-dimensional photonic crystal layer. The typical plane pattern block diagram of added lattice point 12P for perturbation state formation. (A) Schematic cross-sectional structure diagram along line XIV-XIV in FIG. 92, (b) Schematic cross-sectional structure diagram along line XV-XV in FIG. 92, (c) Schematic structure along line XVI-XVI in FIG. FIG. (A) In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a schematic plan configuration diagram of a lattice point for forming a resonance state of a two-dimensional photonic crystal layer applied to Γ point oscillation (square lattice) Arrangement example), (b) Band structure diagram of a two-dimensional photonic crystal applied to a two-dimensional photonic crystal surface emitting laser according to a ninth embodiment. In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) a lattice state for forming a resonance state of a two-dimensional photonic crystal layer applied to M-point oscillation and a refractive index modulation / hole shape (hole diameter) ) Schematic plane configuration diagram (example of square lattice arrangement) of lattice points for perturbation state formation to which perturbations such as modulation and hole depth modulation are added, (b) of a two-dimensional photonic crystal corresponding to FIG. Band structure diagram. In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) a schematic diagram of a lattice point for forming a resonance state and a lattice point for forming a perturbation state of a two-dimensional photonic crystal layer applied to X-point oscillation (B) Band structure diagram of a two-dimensional photonic crystal corresponding to FIG. 96 (a). In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) a schematic diagram of a lattice point for forming a resonance state and a lattice point for forming a perturbation state of a two-dimensional photonic crystal layer applied to X-point oscillation (B) A band structure diagram of a two-dimensional photonic crystal corresponding to FIG. 97 (a). In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) a schematic diagram of a lattice point for forming a resonance state and a lattice point for forming a perturbation state of a two-dimensional photonic crystal layer applied to J-point oscillation (B) Band structure diagram of a two-dimensional photonic crystal corresponding to FIG. 98 (a). In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) a schematic diagram of a lattice point for forming a resonance state and a lattice point for forming a perturbation state of a two-dimensional photonic crystal layer applied to X-point oscillation FIG. 99 is a schematic plan configuration diagram (example of rectangular lattice arrangement: example of a ₁ > a ₂ ), (b) a band structure diagram of a two-dimensional photonic crystal corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) a schematic diagram of a lattice point for forming a resonance state and a lattice point for forming a perturbation state of a two-dimensional photonic crystal layer applied to X-point oscillation FIG. 4B is a schematic plan view (diamond lattice arrangement example), (b) a band structure diagram of a two-dimensional photonic crystal corresponding to FIG. In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) a schematic diagram of a lattice point for forming a resonance state and a lattice point for forming a perturbation state of a two-dimensional photonic crystal layer applied to X-point oscillation Planar configuration diagram (example of rectangular lattice arrangement: example of a ₁ <a ₂ ), (b) Band structure of a two-dimensional photonic crystal corresponding to FIG. 101 (a), and relationship between normalized frequency and wave number FIG. In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) a schematic diagram of a lattice point for forming a resonance state and a lattice point for forming a perturbation state of a two-dimensional photonic crystal layer applied to X-point oscillation (2) Band structure diagram of a two-dimensional photonic crystal corresponding to FIG. 102 (a). In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the resonance state forming lattice points in the resonator region RP and the perturbation state forming region PP of the two-dimensional photonic crystal layer applied to the X-point oscillation 12A. Arrangement example of perturbed state forming lattice points 12P. In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) an example in which resonance state forming lattice points 12A are arranged in the photonic crystal layer 12, and (b) in the same photonic crystal layer 12 The example which arrange | positioned the lattice point 12A for resonance state formation, and the lattice point 12P for perturbation state formation. In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) the sizes of the resonator region RP and the perturbation state forming region PP of the two-dimensional photonic crystal layer applied to the X-point oscillation are approximately the same. Near field image (NFP) in the case of being equal, (b) Schematic diagram showing a beam expansion region from the perturbation state formation region PP, (c) Resonator region RP and perturbation state corresponding to FIG. 105 (a) An example of real space arrangement when a perturbation is applied in the y-axis direction to the resonance state forming lattice points in the formation region PP. In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) the sizes of the resonator region RP and the perturbation state forming region PP of the two-dimensional photonic crystal layer applied to the X point oscillation are different. (B) Schematic diagram showing the beam expansion region from the perturbation state formation region PP, (c) y-axis direction at the resonance state formation lattice point in the perturbation state formation region PP corresponding to FIG. 106 (a) Example of real space arrangement when perturbation is added to. In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the resonance state forming lattice points in the resonator region RP and the perturbation state forming region PP of the two-dimensional photonic crystal layer applied to M point oscillation 12A. Arrangement example of perturbed state forming lattice points 12P. In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) a real space arrangement example when a perturbation is applied in the y-axis direction to the resonance state forming lattice point of the two-dimensional photonic crystal layer; (B) Example of real space arrangement when perturbation is applied to the resonance state forming lattice point of the two-dimensional photonic crystal layer in the x-axis direction. (C) x is applied to the resonance state forming lattice point of the two-dimensional photonic crystal layer. Example of real space arrangement when perturbation is applied in the direction of plus 45 degrees to the axis, (d) Perturbation is applied to the lattice point for forming the resonance state of the two-dimensional photonic crystal layer in the direction of minus 45 degrees to the x axis An example of real space layout. In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) the sizes of the resonator region RP and the perturbation state forming region PP of the two-dimensional photonic crystal layer applied to the M point oscillation are approximately the same. NFP in the case of being equal, (b) Schematic diagram showing a beam spreading region from the perturbation state formation region PP, (c) Resonance region formation in the resonator region RP and the perturbation state formation region PP corresponding to FIG. 109 (a) An example of real space arrangement when a perturbation is applied to a grid point in the direction of plus 45 degrees with respect to the x-axis. In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, (a) the sizes of the resonator region RP and the perturbation state forming region PP of the two-dimensional photonic crystal layer applied to the M point oscillation are different. (B) Schematic diagram showing a beam expansion region from the perturbation state formation region PP, (c) A resonance state formation lattice point in the perturbation state formation region PP corresponding to FIG. On the other hand, an example of real space arrangement when perturbation is added in the direction of plus 45 degrees. In the two-dimensional photonic crystal surface emitting laser according to the eleventh embodiment, a two-dimensional cell array is used to increase the output. In the two-dimensional photonic crystal surface emitting laser according to the eleventh embodiment, (a) a basic pattern T ₀ of resonance state forming lattice points is arranged on the two-dimensional photonic crystal layer on the first cladding layer; Example of two-dimensional cell array configuration in which perturbation patterns T ₁ , T ₂ , T _3, and T ₄ of rectangular perturbation state forming regions PP1, PP2, PP3, and PP4 are arranged, (b) Two-dimensional photo on the first cladding layer A two-dimensional cell array in which the basic pattern T ₀ of the resonance state forming lattice points is arranged in the nick crystal layer, and the perturbation patterns T ₁ , T ₂ , T ₃ of the hexagonal perturbation state forming regions PP1, PP2, PP3 are arranged Configuration example. In the two-dimensional photonic crystal surface emitting laser according to the eleventh embodiment, a two-dimensional cell array configuration example in which a plurality of chips of the configuration shown in FIG. 112B is arranged on the same substrate. In the two-dimensional photonic crystal surface emitting laser according to the eleventh embodiment, a two-dimensional cell array configuration example in which a plurality of chips having different FFPs are arranged on the same substrate.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the following first to eleventh embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the embodiments of the present invention are components of the present invention. The material, shape, structure, arrangement, etc. are not specified below. Various modifications can be made to the embodiment of the present invention within the scope of the claims.

[First embodiment]
(Element structure)
A schematic bird's-eye view structure of the two-dimensional photonic crystal surface emitting laser according to the first embodiment is expressed as shown in FIG.

  As shown in FIG. 1, the two-dimensional photonic crystal surface emitting laser according to the first embodiment is arranged in a standing wave forming photonic crystal layer 12 and a standing wave forming photonic crystal layer 12. And a resonator lattice point 12A for diffracting a light wave at the M-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 within the plane of the standing wave forming photonic crystal layer 12, and A coupler lattice point 12 </ b> C that diffracts a light wave at the M-point band end in the photonic band structure of the standing wave forming photonic crystal layer 12 in the direction perpendicular to the plane of the standing wave forming photonic crystal layer 12 is provided.

  Here, the coupler lattice point 12 </ b> C is disposed in the standing wave forming photonic crystal layer 12.

  The two-dimensional photonic crystal surface emitting laser according to the first embodiment includes a substrate 24, a first cladding layer 10 disposed on the substrate 24, and a first cladding layer 10 as shown in FIG. A second clad layer 16 disposed above, and an active layer 14 sandwiched between the first clad layer 10 and the second clad layer 16 are provided. Here, the first cladding layer 10 may be a p-type semiconductor layer, and the second cladding layer 16 may be an n-type semiconductor layer, or the conductivity may be reversed.

  Furthermore, as shown in FIG. 1, the two-dimensional photonic crystal surface emitting laser according to the first embodiment includes a contact layer 18 disposed on the second cladding layer 16 and a surface emitting region on the contact layer 18. And a window layer 20 for extracting laser light, a window-shaped upper electrode 22 disposed on the window layer 20, and a lower electrode 26 disposed on the back surface of the substrate 24.

  As shown in FIG. 1, the standing wave forming photonic crystal layer 12 is adjacent to the active layer 14 between the first cladding layer 10 and the second cladding layer 16 in the direction perpendicular to the surface of the active layer 14. It may be arranged. Here, the active layer 14 may be formed of, for example, a multi-quantum well (MQW) layer.

  Further, as shown in FIG. 1, a carrier block layer 13 is provided between the active layer 14 and the standing wave forming photonic crystal layer 12, and carriers are effectively taken into the active layer 14 composed of an MQW layer. In addition, the inflow of carriers from the active layer 14 to the standing wave forming photonic crystal layer 12 may be blocked.

As a material system of the two-dimensional photonic crystal surface emitting laser according to the first embodiment, for example, the following can be applied. That is, for example, at a wavelength of 1.3 μm to 1.5 μm, a GaInAsP / InP system, an infrared light with a wavelength of 900 nm is an InGaAs / GaAs system, and an infrared light / near infrared light with a wavelength of 800 nm to 900 is GaAlAs / GaAs. GaAlInAs / GaAs system, GaAlInAs / InP system for wavelengths of 1.3 μm to 1.67 μm, AlGaInP / GaAs system for wavelengths of 0.65 μm, GaInN / GaN system for blue light, etc. are applicable.

  2 is a band structure of a two-dimensional photonic crystal applied to the two-dimensional photonic crystal surface emitting laser according to the first embodiment, and the relationship between the normalized frequency [unit: c / a] and the wave vector is shown in FIG. As shown in FIG.

  In the photonic band structure, a portion where the inclination is 0 is called a band edge. At the band edge, the group velocity of light becomes 0 and a standing wave is formed, so that the photonic crystal functions as a light resonator.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, oscillation at the M-point band end (near the Q region in FIG. 2) in the photonic band structure of the standing wave forming photonic crystal layer 12 is performed. We are using.

  In the standing wave forming photonic crystal layer 12, the resonator lattice points 12 </ b> A are applied to diffraction within the plane of the standing wave forming photonic crystal layer 12. On the other hand, the coupler lattice point 12 </ b> C is applied to diffraction in the direction perpendicular to the surface of the standing wave forming photonic crystal layer 12.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, a schematic explanatory diagram of the in-plane resonance mode of the two-dimensional photonic crystal layer 12 is expressed as shown in FIG. FIG. 3A shows a state in which a two-dimensional large-area resonator is formed by the multiplexed in-plane resonance mode in which the resonator lattice point 12A in the two-dimensional photonic crystal layer 12 is a cavity. It is shown.

  In the two-dimensional photonic crystal surface emitting laser according to the comparative example, the schematic plane configuration of the resonator lattice point 12A of the two-dimensional photonic crystal layer 12 applied to the Γ-point oscillation is a square lattice as shown in FIG. Placed in.

At the oscillation band edge using the Γ point band edge (near the P region in FIG. 2), in the standing wave forming photonic crystal layer 12, the resonator lattice point 12A functions as both a resonator and a coupler. The surface emitting laser light hν _L can be extracted in the direction perpendicular to the surface of the standing wave forming photonic crystal layer 12 with the configuration of 3 (a).

  On the other hand, since the M point oscillation band end and the X point oscillation band end have only a function of a resonator, it is possible to extract light by introducing a photonic crystal structure having a coupler function in an overlapping manner.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, oscillation at the M-point band edge of the photonic band structure is used. In these oscillations, the periodic structure of the photonic crystal has only a function of forming a standing wave for oscillation, but a periodic structure (coupler) for diffracting light is provided in the same plane as this periodic structure. By providing, light can be extracted.

  Moreover, the two-dimensional photonic crystal surface emitting laser according to the first embodiment can operate in a large area and a stable single mode. That is, in the two-dimensional photonic crystal surface emitting laser according to the first embodiment, a two-dimensional structure including resonator lattice points 12A and coupler lattice points 12C formed in the standing wave forming photonic crystal layer 12 is used. Since the electromagnetic field distribution is defined by the periodic structure, a single mode can be maintained even in a large area. For this reason, for example, processing such as focusing W-class output light on a small point via a lens is easy.

  For example, in FIG. 1, the size of the standing wave forming photonic crystal layer 12 is, for example, about 700 μm × about 700 μm.

  Further, in the example of a near field image (NFP), a large area oscillation of about 100 μm square to an ultra large area oscillation of about several hundred μm square can be realized. The oscillation spectrum is obtained, for example, at room temperature continuous oscillation at a wavelength of about 950 nm with a full width at half maximum (FWHM) of about 0.16 nm. Further, in a single mode, a light output of 2.7 W is obtained by pulse driving of 1 kHz-50 ns.

In FIG. 3A, although the illustration of the coupler lattice point 12C is omitted, the surface emitting laser light hν _L is emitted in the vertical direction with respect to the photonic crystal layer 12.

The emitted surface emitting laser beam hν _L and the intracavity laser beam hν _R are expressed as shown in FIG. The surface emitting laser light hν _L is emitted in a direction perpendicular to the photonic crystal layer 12 as a combination of four waves of the intracavity laser light hν _{R in} the surface of the photonic crystal layer 12.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the schematic plane configuration of the resonator lattice point 12A and the coupler lattice point 12C of the two-dimensional photonic crystal layer 12 applied to M point oscillation is as follows. As shown in FIG. 5A, they are arranged in a square lattice. Moreover, it is a band structure of the two-dimensional photonic crystal corresponding to FIG. 5A, and the relationship between the normalized frequency and the wave number vector is expressed as shown in FIG. 5B.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, as shown in FIG. 5A and FIG. 5B, in the photonic band structure of the standing wave forming photonic crystal layer 12 The resonator lattice point 12A for diffracting the light wave at the M-point band edge is disposed in a square lattice, and the coupler lattice point 12C is disposed in a face-centered square lattice having a lattice constant twice that of the square lattice. The pitch of the coupler lattice points 12C in the diagonal direction is equal to the in-medium wavelength λ of the photonic crystal layer 12.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, enlarged schematic views of the resonator lattice points 12A and the coupler lattice points 12C of the two-dimensional photonic crystal layer 12 applied to M-point oscillation. A planar configuration (an example of a square lattice arrangement) is represented as shown in FIG. 6, and a schematic cross-sectional structure taken along line II-II in FIG. 6 is represented as shown in FIG. A schematic cross-sectional structure along the line -III is expressed as shown in FIG.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the resonator lattice point 12A and the coupler lattice point 12C of the two-dimensional photonic crystal layer 12 applied to the M-point oscillation are shown in FIG. ) And as shown in FIG. 7 (b).

  The resonator lattice points 12A and the coupler lattice points 12C can be arranged, for example, at a pitch of about the light period. For example, if the holes are filled with air, the air / semiconductor pitch can be arranged in a period of about 400 nm in the optical communication band, and can be arranged in a period of about 230 nm in blue light. .

  In addition, the diameter and depth of the resonator lattice point 12A and the coupler lattice point 12C that are prototyped are about 120 nm and 115 nm, for example, and the pitch is about 286 nm, for example. These numerical examples can be appropriately changed depending on the material system constituting the substrate 10 and the active layer 14, the material system of the two-dimensional photonic crystal layer 12, the wavelength in the medium, and the like.

  For example, in the two-dimensional photonic crystal surface emitting laser according to the first embodiment to which a GaAs / AlGaAs-based material is applied, the in-medium wavelength λ of the two-dimensional photonic crystal layer 12 is about 200 nm to about 300 nm. The output light wavelength is about 900 nm to about 915 nm.

  The resonator lattice points 12A and the coupler lattice points 12C may be filled with semiconductor layers having different refractive indexes, instead of being formed as air holes, for example. For example, the GaAs layer may be formed by filling an AlGaAs layer. For example, in the manufacturing process of fusing the two-dimensional photonic crystal layer 12, when the cavity shapes of the resonator lattice points 12A and the coupler lattice points 12C are deformed, the semiconductor layers having different refractive indexes may be filled. This is effective in avoiding such deformation.

  A schematic cross-sectional structure of the two-dimensional photonic crystal surface emitting laser according to the first embodiment taken along line II in FIG. 5 is expressed as shown in FIG.

  That is, the two-dimensional photonic crystal surface emitting laser according to the first embodiment includes a substrate (24: FIG. 1), a first cladding layer 10 disposed on the substrate (24), and the first cladding layer 10. The standing clad layer-forming photonic crystal layer 12 includes a first clad layer 16 disposed thereon, and an active layer 14 sandwiched between the first clad layer 10 and the second clad layer 16. 10 and the active layer 14 may be disposed adjacent to each other in the direction perpendicular to the surface of the active layer 14. Further, as shown in FIG. 8, a carrier block layer 13 is provided between the standing wave forming photonic crystal layer 12 and the active layer 14.

(Modification 1)
A schematic cross-sectional structure of a two-dimensional photonic crystal surface emitting laser according to the first modification of the first embodiment along the line II in FIG. 5 is represented as shown in FIG.

  That is, in the two-dimensional photonic crystal surface emitting laser according to the first modification of the first embodiment, as shown in FIG. 9A, the standing wave forming photonic crystal layer 12 includes the second cladding layer. 16 and the active layer 14 may be disposed adjacent to each other in the direction perpendicular to the surface of the active layer 14. Although not shown in FIG. 10A, a carrier block layer 13 is arranged between the standing wave forming photonic crystal layer 12 and the active layer 14 as in FIG. Also good.

(Modification 2)
A schematic cross-sectional structure of a two-dimensional photonic crystal surface emitting laser according to the second modification of the first embodiment along the line II in FIG. 5 is expressed as shown in FIG.

In other words, the two-dimensional photonic crystal surface-emitting laser according to the second modification of the first embodiment, as shown in FIG. 9 (b), is laminated with the photonic crystal layer 12 ₁ for the standing wave formed The light emitting photonic crystal layer 12 ₂ may be further provided, and the coupler lattice point 12C may be disposed in the light emitting photonic crystal layer 12 ₂ .

The two-dimensional photonic crystal surface emitting laser according to the second modification of the first embodiment is disposed on the substrate (24: FIG. 1) and the substrate (24) as shown in FIG. 9B. The first clad layer 10, a second clad layer 16 disposed on the first clad layer 10, and an active layer 14 sandwiched between the first clad layer 10 and the second clad layer 16, and standing wave formation The photonic crystal layer 12 ₁ for light and the photonic crystal layer 12 ₂ for light emission sandwich the active layer 14 between the first cladding layer 10 and the second cladding layer 16 in the direction perpendicular to the surface of the active layer 14. Be placed.

Although not shown in FIG. 9B, between the standing wave forming photonic crystal layer 12 ₁ and the active layer 14 and between the light emitting photonic crystal layer 12 ₂ and the active layer 14. In the meantime, similarly to FIG. 8, the carrier block layers 13 may be respectively disposed.

Further, in FIG. 9B, the stacking order of the standing wave forming photonic crystal layer 12 ₁ and the light emitting photonic crystal layer 12 ₂ is reversed so that the active layer 14 and the second cladding layer 16 are disposed. the light-emitting photonic crystal layer 12 ₂ is arranged, it may be arranged a photo for the standing wave formed photonic crystal layer ₁₂₁ between the active layer 14 and the first cladding layer 10. Since the light emitting photonic crystal layer 12 ₂ where the coupler lattice point 12C is disposed can be disposed at a position close to the light extraction direction, the light extraction efficiency can be increased.

(Modification 3)
A schematic cross-sectional structure of a two-dimensional photonic crystal surface emitting laser according to Modification 3 of the first embodiment along the line II in FIG. 5 is represented as shown in FIG.

That is, in the two-dimensional photonic crystal surface emitting laser according to the third modification of the first embodiment, the standing wave forming photonic crystal layer 12 ₁ and the light emitting photonic crystal layer 12 ₂ are the second The clad layer 16 and the active layer 14 may be disposed adjacent to each other in the direction perpendicular to the surface of the active layer 14. Further, although not shown in FIG. 10 (a), between the light-emitting photonic crystal layer 12 ₂ and the active layer 14, similarly to FIG. 8, be arranged carrier block layer 13 good.

Further, in FIG. 10A, the standing wave forming photonic crystal layer 12 ₁ and the light emitting photonic crystal layer 12 ₂ are stacked in the reverse order, and the standing wave forming photonic crystal is formed on the active layer 14. The crystal layer 12 ₁ may be disposed, and the light emitting photonic crystal layer 12 ₂ may be disposed on the standing wave forming photonic crystal layer 12 ₁ . Better to place the photonic crystal layer 12 ₁ for the standing wave formed in a position closer to the active layer 14, it is possible to more effectively implement a standing wave forming effect. Further, since the light emitting photonic crystal layer 12 ₂ where the coupler lattice point 12C is disposed can be disposed at a position close to the light extraction direction, the light extraction efficiency can be increased.

(Modification 4)
A schematic cross-sectional structure of a two-dimensional photonic crystal surface emitting laser according to Modification 4 of the first embodiment along the line II in FIG. 5 is expressed as shown in FIG.

That is, in the two-dimensional photonic crystal surface emitting laser according to the fourth modification of the first embodiment, the standing wave forming photonic crystal layer 12 ₁ and the light emitting photonic crystal layer 12 ₂ have the first structure. The clad layer 10 and the active layer 14 may be disposed adjacent to each other in the direction perpendicular to the surface of the active layer 14. Further, although not shown in FIG. 10 (b), the between the standing wave forming photonic crystal layer ₁₂₁ and the active layer 14, similarly to FIG. 8, arranged carrier block layer 13 May be.

Further, in FIG. 10A, the order of stacking the standing wave forming photonic crystal layer 12 ₁ and the light emitting photonic crystal layer 12 ₂ is reversed so that the light emitting photonic is close to the active layer 14. the crystal layer 12 ₂ may be disposed. Since the light emitting photonic crystal layer 12 ₂ where the coupler lattice point 12C is disposed can be disposed at a position close to the light extraction direction, the light extraction efficiency can be increased.

(Control of beam divergence angle: resonator region RP and coupler region CP)
The resonator region RP, a region resonator grid point 12A is located in the standing wave forming photonic crystal layer 12, 12 _1, and the coupler region CP, the photonic crystal layer 12 for the standing wave formed Alternatively, this is a region where the coupler lattice point 12C is arranged in the light emitting photonic crystal layer 12 ₂ .

In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the relationship among the width A of the coupler region CP, the beam divergence angle, and the beam divergence region is schematically shown in FIGS. ) And FIG. 11 (c). That is, the width A ₁ of the coupler region CP _1, an example of beam spread angle theta _1, and the beam divergence region 30 ₁ is represented as shown in FIG. 11 (a), the width A ₂ of the coupler region CP _2, the beam divergence angle examples of theta _2, and the beam divergence region 30 ₂ is expressed as shown in FIG. 11 (b), the width a ₃ coupler region CP _3, an example of beam spread angle theta _3, and beam spread region 30 ₃ 11 It is expressed as shown in (c). Here, the magnitude relation of the width of the coupler region is A ₁ <A ₂ <A ₃ , the size of the coupler region CP ₁ is relatively small, and the size of the coupler region CP ₃ is relatively large. Further, the magnitude relation between the beam divergence angles that define the beam divergence areas 30 ₁ , 30 _2, and 30 ₃ is such that θ ₁ > θ ₂ > θ ₃ .

In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the magnitude relationship of the resonator region RP corresponding to FIG. 11A, FIG. 11B, and FIG. It is expressed as shown in a), and the magnitude relationship between the beam divergence angles is expressed as shown in FIG. That is, the larger the size of the resonator region RP, the smaller the beam divergence angle θ ₀ .

In the two-dimensional photonic crystal surface emitting laser according to the comparative example, it is a diagram showing the relationship of the size of the resonator region RP of the two-dimensional photonic crystal layer applied to the Γ point oscillation, and an example of RP ₁ is shown in FIG. 13 (a), an example of RP ₂ is represented as shown in FIG. 13 (b), and an example of RP ₃ is represented as shown in FIG. 13 (c).

On the other hand, in the two-dimensional photonic crystal surface emitting laser according to the first embodiment, a diagram showing the relationship between the size of the resonator region RP and the coupler region CP of the two-dimensional photonic crystal layer applied to M-point oscillation. An example of RP ₁ and CP ₁ is represented as shown in FIG. 14A, an example of RP ₂ and CP ₂ is represented as shown in FIG. 14B, and an example of RP ₃ and CP ₃ Is represented as shown in FIG.

To oscillate a two-dimensional photonic crystal surface emitting laser, a resonator region of a certain level or more is required. For Γ point oscillation of the comparative example therefore, an attempt to increase the beam divergence angle theta, can not be ensured that the resonator region RP _A required oscillation. That is, in the two-dimensional photonic crystal surface emitting laser according to the comparative example, since the Γ point oscillation is used, the size of the resonator region RP is directly equal to the size of the coupler region CP. When the size of the resonator region RP is reduced, as shown in FIG. 12A, the resonator region RP _A necessary for oscillation is secured in the range of RP <RP _A in the size relationship of the resonator region RP. Because it is not possible to oscillate.

(Positioning relationship between coupler and resonator)
In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, resonator lattice points 12A and couplers in the resonator region RP and coupler region CP of the two-dimensional photonic crystal layer 12 applied to M-point oscillation An example of the arrangement of the grid points 12C is expressed as shown in FIG.

Further, in the two-dimensional photonic crystal surface-emitting laser according to the first embodiment, an example of arranging the coupler lattice point 12C to the light-emitting photonic crystal layer 12 _2, as shown in FIG. 16 (a) expressed, example in which the resonator grid point 12A on the standing wave forming photonic crystal layer ₁₂₁ is expressed as shown in FIG. 16 (b). Further, an example in which the resonator lattice points 12A and the coupler lattice points 12C are arranged on the same photonic crystal layer 12 is represented as shown in FIG. Another example in which the point 12A and the coupler lattice point 12C are arranged is expressed as shown in FIG. 16D, and the resonator lattice point 12A and the coupler lattice point 12C are arranged in the same photonic crystal layer 12. Yet another example is represented as shown in FIG.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the positional relationship between the coupler lattice point 12C and the resonator lattice point 12A is free as shown in FIGS. 16 (c) to 16 (e). Can be set. The LD characteristics (output, threshold value, etc.) vary depending on the arrangement relationship between the coupler lattice point 12C and the resonator lattice point 12A.

(Beam shape control by coupler arrangement)
In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the NFP in the case where the size of the resonator region RP and the coupler region CP of the two-dimensional photonic crystal layer 12 applied to the M-point oscillation is substantially equal. Is expressed as shown in FIG. 17 (a), and the beam expansion region 30 from the coupler region CP is expressed as shown in FIG. 17 (b), and the resonator region RP corresponding to FIG. 17 (a) and An arrangement example of the resonator lattice points 12A and the coupler lattice points 12C in the coupler region CP is expressed as shown in FIG.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the size of the resonator region RP and the coupler region CP of the two-dimensional photonic crystal layer 12 applied to the M point oscillation is different. NFP is expressed as shown in FIG. 18A, and the beam expansion region 30 from the coupler region CP is expressed as shown in FIG. 18B, and the resonator region RP corresponding to FIG. 18A. An example of the arrangement of the resonator lattice points 12A and the coupler lattice points 12C in the coupler region CP is expressed as shown in FIG.

  That is, in the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the resonator and the coupler can be designed separately, and stable oscillation can be maintained by changing only the coupler arrangement. However, the beam shape of the surface emitting laser light can be variously changed.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the coupler in which the coupler lattice point 12C is disposed while maintaining the size of the resonator region RP in which the resonator lattice point 12A is disposed. By changing the region CP, the size and shape of the light emitting surface of the laser beam can be adjusted while maintaining stable oscillation.

(Other examples of beam generation)
The two-dimensional photonic crystal surface emitting laser according to the first embodiment has a relatively large circular coupler region CP in the resonator region RP of the two-dimensional photonic crystal layer 12 applied to M-point oscillation. The NFP in this case is expressed as shown in FIG. 19A, and the FFP corresponding to FIG. 19A is expressed as shown in FIG. 19B.

  Further, the NFP in the case where the resonator region RP has a relatively small circular coupler region CP is represented as shown in FIG. 20A, and the FFP corresponding to FIG. 20A is shown in FIG. It is expressed as shown in b).

  Further, NFP in the case of having a relatively small circular coupler region CP in the resonator region RP is expressed as shown in FIG. 21A, and the FFP corresponding to FIG. 21A is shown in FIG. It is expressed as shown in (b).

  Further, NFP in the case of having a relatively large oval coupler region CP in the resonator region RP is expressed as shown in FIG. 22A, and the FFP corresponding to FIG. 22A is shown in FIG. It is expressed as shown in (b).

  Further, the NFP when a plurality of relatively small circular coupler regions CP are arranged in the resonator region RP is expressed as shown in FIG. 23A, and the FFP corresponding to FIG. 23 (b).

  Further, the NFP in the case of having two oval coupler regions CP orthogonal to each other in the resonator region RP is expressed as shown in FIG. 24A, and the FFP corresponding to FIG. It is expressed as shown in FIG.

  Further, the NFP in the case of having three oval coupler regions CP intersecting each other at 60 degrees in the resonator region RP is expressed as shown in FIG. 25A and corresponds to FIG. FFP is expressed as shown in FIG.

  Further, the NFP in the case of having two oval coupler regions CP intersecting each other at 120 degrees in the resonator region RP is expressed as shown in FIG. 26A and corresponds to FIG. FFP is expressed as shown in FIG.

  Further, NFP in the case of having five oval coupler regions CP intersecting each other at 72 degrees in the resonator region RP is expressed as shown in FIG. 27A and corresponds to FIG. FFP is expressed as shown in FIG.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, as shown in FIGS. 19 to 27, the size of the oscillation region is maintained in oscillation at the M-point band edge in the photonic band structure. The size and shape of the light emitting surface of the laser beam can be adjusted by relatively changing the size of the coupler region CP. As examples of the size of the NFP, various sizes such as several tens of μm square, several hundreds of μm square, and 1 mm square can be formed, and the same applies to the corresponding FFP.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the beam divergence angle θ and the shape of the laser beam are determined by the size and shape of the light emitting surface of the laser beam. The angle and shape can be controlled. As long as the periodic structure for optical amplification is maintained, oscillation is possible even if the size and shape of the coupler region CP are changed.

  Since the beam divergence angle θ and shape of the laser beam are determined by the size and shape of the light emitting surface, for example, when it is desired to increase the beam divergence angle θ of the laser beam, the size of the resonator region RP for optical amplification is The coupler region CP may be made relatively small as it is. Further, when the laser beam shape is desired to be rectangular, the coupler region CP may be rectangular.

  In particular, since the two-dimensional photonic crystal surface emitting laser according to the first embodiment can control the beam divergence angle θ and the shape of the laser beam, various shapes as shown in FIGS. It can be used for lens-free markers.

  By using the two-dimensional photonic crystal surface emitting laser according to the first embodiment, it is possible to change the divergence angle and shape of the laser beam, and thus the range of applications can be expanded. For example, laser beam printer light source, distance sensor light source, autofocus light source, next generation optical disk pickup light source, laser pointer, laser scan display, barcode scanner, portable device built-in scan display, capsule built-in laser knife, other DVD, It is applicable to a wide range of application fields such as BD and inter-chip communication equipment.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the size of the resonator region RP of the resonator necessary for M-point oscillation is kept as it is, and the size of the coupler region CP is relatively small. As a result, the beam divergence angle θ can be increased.

  According to the first embodiment, it is possible to provide a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle and shape of the laser beam by the coupler arrangement.

[Second Embodiment]
In the two-dimensional photonic crystal surface emitting laser according to the second embodiment, oscillation at the band end of the X point of the photonic band structure is used. In these oscillations, the periodic structure of the photonic crystal has only an optical amplification function for oscillation, but a periodic structure (coupler) for diffracting light is provided in the same plane as this periodic structure. Thus, light can be extracted.

  In the two-dimensional photonic crystal surface emitting laser according to the second embodiment, the schematic plan configuration of the resonator lattice point 12A and the coupler lattice point 12C of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation is as follows. As shown in FIG. 28A, they are arranged in a square lattice. Moreover, it is the band structure of the two-dimensional photonic crystal corresponding to FIG. 28A, and the relationship between the normalized frequency c / a and the wave vector is expressed as shown in FIG.

  The two-dimensional photonic crystal surface emitting laser according to the second embodiment corresponds to the example of the square lattice (X-point oscillation), and the photonic band structure of the standing wave forming photonic crystal layer 12 Oscillation at the X point band end (near the R region in FIG. 28B) is used.

  The two-dimensional photonic crystal surface emitting laser according to the second embodiment includes a standing wave forming photonic crystal layer 12 and a standing wave forming photonic crystal layer 12 as shown in FIG. The lattice point 12 </ b> A for a resonator that is disposed within the surface and diffracts the light wave at the X-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 within the plane of the standing wave forming photonic crystal layer 12. And a lattice point 12C for a coupler that diffracts the light wave at the X-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 in the direction perpendicular to the plane of the standing wave forming photonic crystal layer 12. Prepare.

  In the two-dimensional photonic crystal surface emitting laser according to the second embodiment, the resonator lattice point 12A is arranged in the first square lattice as shown in FIG. 28A, and the coupler lattice point 12C is The lattice constant of the coupler lattice point 12C is equal to the in-medium wavelength λ of the photonic crystal layer, which is arranged in a second square lattice having a lattice constant that is twice the lattice constant of the first square lattice.

  Other configurations are the same as those of the first embodiment and the first to fourth modifications thereof.

  In the two-dimensional photonic crystal surface emitting laser according to the second embodiment, the size of the resonator region RP of the resonator necessary for the X-point oscillation is kept as it is, and the size of the coupler region CP is made relatively small. As a result, the beam divergence angle θ can be increased.

  According to the second embodiment, it is possible to provide a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle and shape of the laser beam by the coupler arrangement while maintaining stable oscillation.

[Third Embodiment]
In the two-dimensional photonic crystal surface emitting laser according to the third embodiment, oscillation at the band end of the X point of the photonic band structure is used. In these oscillations, the periodic structure of the photonic crystal has only an optical amplification function for oscillation, but a periodic structure (coupler) for diffracting light is provided in the same plane as this periodic structure. Thus, light can be extracted.

  In the two-dimensional photonic crystal surface emitting laser according to the third embodiment, the schematic plan configuration of the resonator lattice point 12A and the coupler lattice point 12C of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation is as follows. As shown in FIG. 29A, they are arranged in a triangular lattice. Moreover, it is the band structure of the two-dimensional photonic crystal corresponding to FIG. 29A, and the relationship between the normalized frequency c / a and the wave vector is expressed as shown in FIG.

  The two-dimensional photonic crystal surface emitting laser according to the third embodiment corresponds to the example of the triangular lattice (X-point oscillation), and the photonic band structure of the standing wave forming photonic crystal layer 12 Oscillation at the X point band edge (near the R region in FIG. 29B) is used.

  As shown in FIG. 29A, the two-dimensional photonic crystal surface emitting laser according to the third embodiment includes a standing wave forming photonic crystal layer 12 and a standing wave forming photonic crystal layer 12. The lattice point 12 </ b> A for a resonator that is disposed within the surface and diffracts the light wave at the X-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 within the plane of the standing wave forming photonic crystal layer 12. And a lattice point 12C for a coupler that diffracts the light wave at the X-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 in the direction perpendicular to the plane of the standing wave forming photonic crystal layer 12. Prepare.

  In the two-dimensional photonic crystal surface emitting laser according to the third embodiment, as shown in FIG. 29A, the resonator lattice point 12A is arranged in the first triangular lattice, and the coupler lattice point 12C is The height in plan view of the second triangular lattice is equal to the in-medium wavelength λ of the photonic crystal layer 12, which is disposed in the second triangular lattice having a pitch twice the pitch of the first triangular lattice.

  Other configurations are the same as those of the first embodiment and the first to fourth modifications thereof.

  In the two-dimensional photonic crystal surface emitting laser according to the third embodiment, the size of the resonator region RP of the resonator necessary for the X-point oscillation is kept as it is, and the size of the coupler region CP is made relatively small. As a result, the beam divergence angle θ can be increased.

  According to the third embodiment, it is possible to provide a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle and shape of the laser beam by the coupler arrangement while maintaining stable oscillation.

[Fourth embodiment]
In the two-dimensional photonic crystal surface emitting laser according to the fourth embodiment, oscillation at the band edge of point J of the photonic band structure is used. In these oscillations, the periodic structure of the photonic crystal has only an optical amplification function for oscillation, but a periodic structure (coupler) for diffracting light is provided in the same plane as this periodic structure. Thus, light can be extracted.

  In the two-dimensional photonic crystal surface emitting laser according to the fourth embodiment, the schematic plane configuration of the resonator lattice point 12A and the coupler lattice point 12C of the two-dimensional photonic crystal layer 12 applied to the J-point oscillation is as follows. As shown in FIG. 30A, they are arranged in a triangular lattice. Further, the band structure of the two-dimensional photonic crystal corresponding to FIG. 30A, and the relationship between the normalized frequency c / a and the wave vector is expressed as shown in FIG.

  The two-dimensional photonic crystal surface emitting laser according to the fourth embodiment corresponds to an example of a triangular lattice (J point oscillation), and the photonic band structure of the standing wave forming photonic crystal layer 12 Oscillation at the band edge of J point (near the S region in FIG. 30B) is used.

  As shown in FIGS. 30A and 30B, the two-dimensional photonic crystal surface emitting laser according to the fourth embodiment includes a standing wave forming photonic crystal layer 12 and a standing wave formation. The light wave at the J-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 is diffracted in the plane of the standing wave forming photonic crystal layer 12. Coupler that diffracts the light wave at the J-point band edge in the photonic band structure of the resonator wave point 12A and the standing wave forming photonic crystal layer 12 in the direction perpendicular to the plane of the standing wave forming photonic crystal layer 12 Grid point 12C.

In the two-dimensional photonic crystal surface emitting laser according to the fourth embodiment, as shown in FIG. 30A, the resonator lattice point 12A is arranged in the first triangular lattice, and the coupler lattice point 12C is It is arranged in a face-centered triangular lattice having a pitch three times that of the first triangular lattice, and one side of the face-centered triangular lattice is equal to twice the in-medium wavelength λ of the photonic crystal layer 12.

  Other configurations are the same as those of the first embodiment and the first to fourth modifications thereof.

  In the two-dimensional photonic crystal surface emitting laser according to the fourth embodiment, the size of the resonator region RP of the resonator necessary for J-point oscillation is kept as it is, and the size of the coupler region CP is relatively small. As a result, the beam divergence angle θ can be increased.

  According to the fourth embodiment, it is possible to provide a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle and shape of the laser beam by the coupler arrangement while maintaining stable oscillation.

[Fifth embodiment]
In the two-dimensional photonic crystal surface emitting laser according to the fifth embodiment, the schematic plan configuration of the resonator lattice points and coupler lattice points of the two-dimensional photonic crystal layer applied to the X-point oscillation is shown in FIG. As shown to (a), it arrange | positions at a rectangular lattice. Moreover, it is the band structure of the two-dimensional photonic crystal corresponding to FIG. 31A, and the relationship between the normalized frequency c / a and the wave vector is expressed as shown in FIG.

  The two-dimensional photonic crystal surface emitting laser according to the fifth embodiment corresponds to the example of the rectangular lattice (X-point oscillation), and the photonic band of the standing wave forming photonic crystal layer 12 Oscillation at the X-point band edge (near the R region in FIG. 31B) in the structure is used.

  As shown in FIGS. 31A and 31B, the two-dimensional photonic crystal surface emitting laser according to the fifth embodiment includes a standing wave forming photonic crystal layer 12 and a standing wave formation. The light wave at the X-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 is diffracted in the plane of the standing wave forming photonic crystal layer 12. Coupler for diffracting the light wave at the X-point band edge in the photonic band structure of the resonator wave point 12A and the standing wave forming photonic crystal layer 12 in the direction perpendicular to the plane of the standing wave forming photonic crystal layer 12 Grid point 12C.

In the two-dimensional photonic crystal surface emitting laser according to the fifth embodiment, as shown in FIG. 31A, the resonator lattice point 12A is a _first rectangular lattice having lattice constants a ₁ and a _2. The coupler lattice point 12C is disposed in a second rectangular lattice different from the first rectangular lattice. Here, the lattice constant of the second rectangular lattice is equal to the aspect ratio r = a ₁ / a ₂ (r ≠ 1) defined by the lattice constants a ₁ and a ₂ of the _first rectangular lattice. It is equal to r times the medium wavelength λ and the medium wavelength λ.

  Other configurations are the same as those of the first embodiment and the first to fourth modifications thereof.

In the two-dimensional photonic crystal surface emitting laser according to the fifth embodiment, the size of the resonator region RP of the resonator necessary for the X-point oscillation is kept as it is, and the size of the coupler region CP is relatively small. Thus, the beam divergence angle θ ₀ can be increased.

  According to the fifth embodiment, it is possible to provide a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle and shape of the laser beam by the coupler arrangement while maintaining stable oscillation.

[Sixth embodiment]
In the two-dimensional photonic crystal surface emitting laser according to the sixth embodiment, the schematic plan configuration of the resonator lattice point 12A and the coupler lattice point 12C of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation is as follows. As shown in FIG. 32A, they are arranged in a rhombus lattice. Moreover, it is the band structure of the two-dimensional photonic crystal corresponding to FIG. 32A, and the relationship between the normalized frequency c / a and the wave vector is expressed as shown in FIG.

  The two-dimensional photonic crystal surface emitting laser according to the sixth embodiment corresponds to an example of a rhombic lattice (X-point oscillation), and the photonic band structure of the standing wave forming photonic crystal layer 12 Oscillation at the X point band edge (near the R region in FIG. 32B) is used.

  As shown in FIGS. 32A and 32B, the two-dimensional photonic crystal surface emitting laser according to the sixth embodiment includes a standing wave forming photonic crystal layer 12 and a standing wave formation. The light wave at the X-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 is diffracted in the plane of the standing wave forming photonic crystal layer 12. Coupler for diffracting the light wave at the X-point band edge in the photonic band structure of the resonator wave point 12A and the standing wave forming photonic crystal layer 12 in the direction perpendicular to the plane of the standing wave forming photonic crystal layer 12 Grid point 12C.

In the two-dimensional photonic crystal surface emitting laser according to the sixth embodiment, the resonator lattice point 12A is a face-centered rectangular lattice having lattice constants a ₁ and a ₂ as shown in FIG. The grid points 12C for couplers are arranged in a rectangular grid. Here, the lattice constant of the rectangular lattice is the in-medium wavelength λ with respect to the aspect ratio r = a ₁ / a ₂ (r ≠ 1) defined by the lattice constants a ₁ and a ₂ of the face-centered rectangular lattice. Is equal to r times and the in-medium wavelength λ.

  Other configurations are the same as those of the first embodiment and the first to fourth modifications thereof.

In the two-dimensional photonic crystal surface emitting laser according to the sixth embodiment, the size of the resonator region RP of the resonator necessary for the X-point oscillation is kept as it is, and the size of the coupler region CP is made relatively small. Thus, the beam divergence angle θ ₀ can be increased.

  According to the sixth embodiment, it is possible to provide a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle and shape while maintaining stable oscillation.

(Relationship between the diameter D _c of the diameter D _r and couplers lattice point 12C of the resonator grid points 12A)
FIG. 33A shows an arrangement example in which the diameter D _r of the resonator lattice point 12A and the diameter D _c of the coupler lattice point 12C are different and arranged at the same point with D _c ≦ D _r . The example shown in FIG. 33 and arranged at the same point with D _c > D _r is expressed as shown in FIG.

Oscillation even when the relationship between a diameter D _c of the diameter D _r and couplers lattice point 12C of the resonator grid points 12A is what is possible. However, as shown in FIG. 33A, when D _c ≦ D _r and the hole of the coupler lattice point 12C and the hole of the resonator lattice point 12A completely overlap, resonance occurs inside the laser. However, it cannot function as a laser diode because light cannot be extracted.

Further, as shown in FIG. 33B, the resonator lattice point 12A and the coupler lattice point 12C have a circular shape, and the diameter D _c of the coupler lattice point 12C is the diameter D _r of the resonator lattice point 12A. It may be formed larger than.

  On the other hand, when the coupler lattice point 12C and the resonator lattice point 12A are formed in different two-dimensional photonic crystal layers, there is no limitation.

  In the two-dimensional photonic crystal surface emitting laser according to the first embodiment, the resonator lattice point 12A and the coupler lattice point 12C have arbitrary shapes, and the coupler lattice point 12C is more than the resonator lattice point 12A. It may be formed large.

FIG. 33A and FIG. 33B are examples of the two-dimensional photonic crystal layer 12 applied to M-point oscillation, and the two-dimensional photonic crystal surface emitting laser according to the first embodiment is used. Although correspondingly relation diameter D _c of the diameter D _r and couplers lattice point 12C of the resonator grid points 12A, a similar relationship holds also in the second to sixth embodiment of the others.

(Shape of grid points (holes))
FIG. 34A shows an arrangement example in which the shape of the resonator lattice point 12A is different from the shape of the coupler lattice point 12C, where the resonator lattice point 12A has a circular shape and the coupler lattice point 12C has a triangular shape. 34), an example in which the resonator lattice point 12A has a rhombus shape and the coupler lattice point 12C has an oval shape is represented as shown in FIG.

  The resonator lattice point 12A and the coupler lattice point 12C may have a polygonal shape, a circular shape, an elliptical shape, or an oval shape. Here, the polygon includes a triangle, a quadrangle, a pentagon, a hexagon, an octagon, and the like.

  Further, the shape of the lattice point may be different between the coupler lattice point 12C and the resonator lattice point 12A as described below. Moreover, the direction of the shape of the lattice points may be inclined. When the direction of the shape of the lattice point is inclined, the laser beam affects the laser characteristics, for example, the beam shape changes.

  34 (a) and 34 (b) are examples of the two-dimensional photonic crystal layer 12 applied to M-point oscillation, and the two-dimensional photonic crystal surface emitting laser according to the first embodiment is used. Correspondingly, the relationship of the shape of the (hole) between the resonator lattice point 12A and the coupler lattice point 12C is the same in the other second to sixth embodiments.

  As described above, according to the present invention, it is possible to provide a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle and shape of the laser beam by the coupler arrangement.

[Seventh embodiment]
(Element structure)
A schematic bird's-eye view structure of the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment is expressed as shown in FIG.

As shown in FIG. 35, the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment is disposed in the standing wave forming photonic crystal layer 12 and the standing wave forming photonic crystal layer 12. The optical wave at the Γ-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 is diffracted in the plane of the standing wave forming photonic crystal layer 12 and diffracted in the direction perpendicular to the plane. A lattice point 12A for resonators of a rectangular lattice is provided. Here, if the lattice constants of the rectangular lattice are a ₁ and a ₂ , one side a ₁ of the rectangular lattice is equal to the wavelength in the medium.

Further, the aspect ratio r = a ₁ / a ₂ defined by the lattice constants a ₁ and a ₂ may be set to 0.5 <r <1.5 (r ≠ 1).

  In addition, as shown in FIG. 35, the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment includes a substrate 24, a first cladding layer 10 disposed on the substrate 24, and a first cladding layer 10. A second clad layer 16 disposed above, and an active layer 14 sandwiched between the first clad layer 10 and the second clad layer 16 are provided. Here, the first cladding layer 10 may be a p-type semiconductor layer, and the second cladding layer 16 may be an n-type semiconductor layer, or the conductivity may be reversed.

  Furthermore, the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment includes a contact layer 18 disposed on the second cladding layer 16 and a surface emitting region on the contact layer 18 as shown in FIG. And a window layer 20 for extracting laser light, a window-shaped upper electrode 22 disposed on the window layer 20, and a lower electrode 26 disposed on the back surface of the substrate 24.

  As shown in FIG. 35, the standing wave forming photonic crystal layer 12 is adjacent to the active layer 14 in the direction perpendicular to the surface of the active layer 14 between the first cladding layer 10 and the second cladding layer 16. It may be arranged. Here, the active layer 14 may be formed of, for example, a multiple quantum well (MQW) layer.

  Further, as shown in FIG. 35, a carrier block layer 13 is provided between the active layer 14 and the standing wave forming photonic crystal layer 12, and carriers are effectively taken into the active layer 14 composed of the MQW layer. In addition, the inflow of carriers from the active layer 14 to the standing wave forming photonic crystal layer 12 may be blocked.

As a material system of the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, for example, the following can be applied. That is, for example, at a wavelength of 1.3 μm to 1.5 μm, a GaInAsP / InP system, an infrared light with a wavelength of 900 nm is an InGaAs / GaAs system, and an infrared light / near infrared light with a wavelength of 800 nm to 900 is GaAlAs / GaAs. GaAlInAs / GaAs system, GaAlInAs / InP system for wavelengths of 1.3 μm to 1.67 μm, AlGaInP / GaAs system for wavelengths of 0.65 μm, GaInN / GaN system for blue light, etc. are applicable.

  An example of a far field pattern (FFP) having a vertically long beam structure emitted from the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment is expressed as shown in FIG.

In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, a rectangular lattice having one side equal to the wavelength in the medium is used as the lattice structure of the photonic crystal capable of controlling the beam divergence angle θ ₀ emitted from the line beam. (A ₁ = λ) was introduced. By introducing a rectangular lattice, the beam divergence angle θ ₀ can be increased while maintaining a two-dimensional oscillation. If the beam divergence angle θ ₀ can be controlled, the range of applications will be expanded and the value as a beam scanning laser will be improved.

  FIG. 2 shows the band structure of a two-dimensional photonic crystal applied to the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, and the relationship between the normalized frequency (unit: c / a) and the wave number is shown in FIG. It is expressed in the same way.

  In the photonic band structure, a portion where the inclination is 0 is called a band edge. At the band edge, the group velocity of light becomes 0 and a standing wave is formed, so that the photonic crystal functions as a light resonator.

  In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, oscillation at the Γ point band end (near the P region in FIG. 2) in the photonic band structure of the standing wave forming photonic crystal layer 12 is performed. We are using.

  In the standing wave forming photonic crystal layer 12, in the Γ-point band edge oscillation, the resonator lattice point 12A is applied to the in-plane diffraction of the standing wave forming photonic crystal layer 12 and is in the direction perpendicular to the plane. Applies to diffraction into

  In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, a schematic explanatory diagram of the in-plane resonance mode in the Γ-point oscillation of the two-dimensional photonic crystal layer 12 is as shown in FIG. expressed. FIG. 37A shows a state in which a two-dimensional large-area resonator is formed by the multiplexed in-plane resonance mode in which the resonator lattice point 12A in the two-dimensional photonic crystal layer 12 is a cavity. It is shown.

At the oscillation band edge using the Γ point band edge (near the P region in FIG. 3), in the standing wave forming photonic crystal layer 12, the resonator lattice point 12A functions as both a resonator and a coupler. The surface emitting laser light hν _L can be extracted in the direction perpendicular to the plane of the standing wave forming photonic crystal layer 12 with the configuration of 37 (a).

  Moreover, the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment can operate in a large area and a stable single mode. That is, in the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, the electromagnetic field distribution is obtained by the two-dimensional periodic structure including the resonator lattice points 12A formed in the standing wave forming photonic crystal layer 12. Therefore, it is possible to maintain a single mode even in a large area. For this reason, for example, processing such as focusing W-class output light on a small point via a lens is easy.

  For example, in FIG. 35, the size of the standing wave forming photonic crystal layer 12 is, for example, about 700 μm × about 700 μm.

The emitted surface emitting laser beam hν _L and the intracavity laser beam hν _R are expressed as shown in FIG. A plurality of waves of the intracavity laser light hν _R in the surface of the photonic crystal layer 12 are coupled and resonated, and the surface emitting laser light hν _L is emitted in a direction perpendicular to the photonic crystal layer 12.

In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, the resonator lattice point 12A of the two-dimensional photonic crystal layer 12 applied to the Γ-point oscillation has a lattice constant as shown in FIG. Arranged in a rectangular lattice designated as a ₁ and a ₂ . Here, one side a ₁ of the rectangular lattice is equal to the in-medium wavelength λ.

  Further, a schematic cross-sectional structure taken along line IV-IV in FIG. 38 is represented as shown in FIG. 39A, and a schematic cross-sectional structure taken along line V-V in FIG. 38 is shown in FIG. Represented as shown.

  In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, the resonator lattice point 12A of the two-dimensional photonic crystal layer 12 applied to the Γ-point oscillation is shown in FIGS. 39 (a) and 39 (b). ) As shown in FIG.

  In addition, the diameter and depth of the resonator lattice point 12A that has been prototyped are, for example, about 120 nm and 115 nm, and the pitch is, for example, about 280 nm. These numerical examples can be appropriately changed depending on the material system constituting the substrate 10 and the active layer 14, the material system of the two-dimensional photonic crystal layer 12, the wavelength in the medium, and the like.

  For example, in the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment to which a GaAs / AlGaAs-based material is applied, the in-medium wavelength λ of the two-dimensional photonic crystal layer 12 is about 200 nm to about 300 nm. The output light wavelength is about 900 nm to about 915 nm.

  The resonator lattice points 12A may be filled with, for example, semiconductor layers having different refractive indexes instead of being formed as air holes. For example, the GaAs layer may be formed by filling an AlGaAs layer.

  For example, in the manufacturing process of fusing the two-dimensional photonic crystal layer 12, when the cavity shapes of the resonator lattice points 12A and the coupler lattice points 12C are deformed, the semiconductor layers having different refractive indexes may be filled. This is effective in avoiding such deformation.

  The two-dimensional photonic crystal surface emitting laser according to the seventh embodiment has a band structure in the case of an aspect ratio r = 1.015 in rectangular lattice Γ-point oscillation, and has a normalized frequency (c / a) and The relationship with the wave number is expressed as shown in FIG.

  Further, the band structure when the aspect ratio r = 1.03 in the rectangular lattice Γ point oscillation is expressed as shown in FIG. 41, and the band structure when the aspect ratio r = 1.045 in the rectangular lattice Γ point oscillation is shown. The structure is represented as shown in FIG.

In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, as shown by the arrows in FIGS. 40 to 42, the Γ-point oscillation of the rectangular lattice has a wavenumber k spread and an aspect ratio. The spread of the wave number k can be controlled by the value of r (= a ₁ / a ₂ ) (r ≠ 1). That is, since the wave number k corresponds to the radiation angle, the beam divergence angle θ ₀ can be controlled.

  In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, the real space of the resonator lattice point 12A of the rectangular lattice is represented as shown in FIG. 43, and the wave number space of the rectangular lattice is 44. As shown in FIG.

In FIG. 43, the lattice constant a ₁ is equal to the in-medium wavelength λ of the two-dimensional photonic crystal layer 12, and the aspect ratio r is a ₁ / a ₂ (r ≠ 1). In FIG. 44, b ₁ = 2π / a ₁ and b ₂ = 2π / a ₂ , and k _f represents the wave number vector of the fundamental wave.

In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, in order to cause the resonator lattice point 12A of the rectangular lattice of the two-dimensional photonic crystal layer 12 to Γ-point oscillate, the gain peak of the active layer 14 is used. Furthermore, the wavelengths of the resonance modes need to overlap. That is, at the Γ point, the wave number k _{f of the} fundamental wave becomes the center wavelength (λ _PC ) in the medium of the active layer gain, and thus the following relationship is obtained.

k _f = | b ₁ | = | (2π / a ₁ , 0) | = 2π / a ₁ = 2π / λ _PC (1)

Therefore, the relationship between the lattice constant a and the center wavelength λ _PC is

a ₁ = λ _PC = λ _air / n _eff (2)

Given in. In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, the center wavelength of the active layer is λ _air = 940 nm and the effective refractive index n _eff = 3.4 in the _air .

(Experimental result)
In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, the FFP measurement experiment result when the aspect ratio r = 1.015 in the rectangular lattice Γ-point oscillation is expressed as shown in FIG. The FFP measurement experiment result when the aspect ratio r = 1.03 in the rectangular lattice Γ point oscillation is expressed as shown in FIG. 46, and the aspect ratio r = 1.045 in the rectangular lattice Γ point oscillation is shown. The measurement experiment result of FFP is expressed as shown in FIG.

In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, as indicated by the arrows in FIGS. 45 to 47, the beam divergence angle θ ₀ is 8 °, 15 °, and 21 °, respectively. It has been.

In the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment, as shown in FIGS. 45 to 47, the length of the two-dimensional photonic crystal surface emitting laser is increased depending on the aspect ratio r (= a ₁ / a ₂ ) (r ≠ 1). It is possible to control the beam divergence angle θ ₀ of the Γ point oscillation of the rectangular lattice. In particular, the longitudinal beam divergence angle can be controlled by the value of the aspect ratio r (= a ₁ / a ₂ ) (r ≠ 1) of the rectangular lattice.

  A schematic cross-sectional structure of the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment taken along line IV-IV in FIG. 38 is expressed as shown in FIG. A schematic cross-sectional structure of the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment along the line is expressed as shown in FIG.

  That is, the two-dimensional photonic crystal surface emitting laser according to the seventh embodiment has a substrate (24: FIG. 1) and a substrate (24) as shown in FIGS. 48 (a) and 48 (b). A first cladding layer 10 disposed on the first cladding layer 10, a second cladding layer 16 disposed on the first cladding layer 10, and an active layer 14 sandwiched between the first cladding layer 10 and the second cladding layer 16. The standing wave forming photonic crystal layer 12 may be disposed between the first cladding layer 10 and the active layer 14 so as to be adjacent to the active layer 14 in the direction perpendicular to the plane. Further, as shown in FIGS. 48A and 48B, a carrier block layer 13 may be provided between the standing wave forming photonic crystal layer 12 and the active layer 14.

(Modification)
A schematic cross-sectional structure of a two-dimensional photonic crystal surface emitting laser according to a modification of the seventh embodiment along the line IV-IV in FIG. 38 is expressed as shown in FIG. A schematic cross-sectional structure along the VV line is expressed as shown in FIG.

  That is, in the two-dimensional photonic crystal surface emitting laser according to the modification of the seventh embodiment, the standing wave forming photonic crystal layer 12 is formed as shown in FIGS. 49 (a) and 49 (b). The second cladding layer 16 and the active layer 14 may be disposed adjacent to each other in the direction perpendicular to the surface of the active layer 14.

  According to the seventh embodiment and its modification, it is possible to provide a two-dimensional photonic crystal surface emitting laser that emits a line beam.

  According to the seventh embodiment and the modification thereof, it is possible to provide a two-dimensional photonic crystal surface emitting laser in which the beam divergence angle of the Γ point oscillation can be controlled by the aspect ratio of the rectangular lattice.

[Eighth embodiment]
The two-dimensional photonic crystal surface emitting laser according to the eighth embodiment is disposed on the substrate 24, the first cladding layer 10 disposed on the substrate 24, and the first cladding layer 10, as in FIG. And the active layer 14 sandwiched between the first cladding layer 10 and the second cladding layer 16.

  Further, the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment is similar to FIG. 35 in that the contact layer 18 disposed on the second cladding layer 16 and the surface emitting region on the contact layer 18 are formed. A window layer 20 that is disposed and for extracting laser light, a window-shaped upper electrode 22 disposed on the window layer 20, and a lower electrode 26 disposed on the back surface of the substrate 24 are provided.

  As in FIG. 35, the standing wave forming photonic crystal layer 12 is disposed between the first cladding layer 10 and the second cladding layer 16 and adjacent to the active layer 14 in the direction perpendicular to the surface of the active layer 14. May be. Here, the active layer 14 may be formed of, for example, an MQW layer.

  Further, a carrier block layer 13 is provided between the active layer 14 and the standing wave forming photonic crystal layer 12, as in FIG. 35, and carriers are effectively taken into the active layer 14 composed of the MQW layer. The inflow of carriers from the active layer 14 to the standing wave forming photonic crystal layer 12 may be blocked.

As a material system of the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, for example, the following can be applied. That is, for example, at a wavelength of 1.3 μm to 1.5 μm, a GaInAsP / InP system, an infrared light with a wavelength of 900 nm is an InGaAs / GaAs system, and an infrared light / near infrared light with a wavelength of 800 nm to 900 is GaAlAs / GaAs. GaAlInAs / GaAs system, GaAlInAs / InP system for wavelengths of 1.3 μm to 1.67 μm, AlGaInP / GaAs system for wavelengths of 0.65 μm, GaInN / GaN system for blue light, etc. are applicable.

  An example of the FFP having the vertically long beam structure emitted also in the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment is the same as that shown in FIG.

In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, as a lattice structure of a photonic crystal capable of controlling the beam divergence angle θ ₀ emitted from the line beam, one side is ½ of the wavelength in the medium. An equal rectangular lattice (a ₁ = λ / 2) was introduced.

  In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, a light wave at the band end of the X point of the photonic band structure is used.

In the light wave at the band edge of the X point, the periodic structure of the photonic crystal has only a function of forming a standing wave for oscillation, but the periodic structure for diffracting light in the same plane as this periodic structure. By providing a (coupler), light can be extracted. By introducing a rectangular lattice, the beam divergence angle θ ₀ can be increased while maintaining a two-dimensional oscillation. If the beam divergence angle θ ₀ can be controlled, the range of applications will be expanded and the value as a beam scanning laser will be improved.

  The two-dimensional photonic crystal surface emitting laser according to the eighth embodiment has a band structure in rectangular lattice X-point oscillation, and the relationship between the normalized frequency (c / a) and the wave number is shown in FIG. It is expressed as follows.

  In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, the real space of the lattice point of the resonator rectangular lattice is expressed as shown in FIG. 51, and the wave number space of the resonator rectangular lattice is It is expressed as shown in FIG.

In FIG. 51, the lattice constant a ₁ is equal to ½ of the in-medium wavelength λ of the two-dimensional photonic crystal layer 12, and the aspect ratio r is = a ₁ / a ₂ (r ≠ 1). In FIG. 52, b ₁ = 2π / a ₁ and b ₂ = 2π / a ₂ , and k _f represents the wave number vector of the fundamental wave.

In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, in order to cause the resonator lattice point 12A of the rectangular lattice of the two-dimensional photonic crystal layer 12 to oscillate at X points, the gain peak of the active layer 14 is obtained. Furthermore, the wavelengths of the resonance modes need to overlap. That is, at the rectangular lattice point X, the wave number k _{f of the} fundamental wave becomes the center wavelength (λ _PC ) in the medium of the active layer gain, and thus the relationship of the following equation is obtained.

k _f = | 1/2 · b ₁ | = | 1/2 · (2π / a ₁ , 0) | = π / a ₁ = 2π / λ _PC
(3)

Therefore, the relationship between the lattice constant a ₁ and the center wavelength λ _PC is

a ₁ = 1/2 · λ _PC = 1/2 · λ _air / n _eff (4)

Given in.

On the other hand, the photonic crystal structure for light emission includes the wave vector k ↑ of light amplified by the standing wave forming photonic crystal structure in the reciprocal lattice vector k space, and the reciprocal lattice vector in the photonic crystal structure for light emission. k _G ↑ is the sum of the wave vector _{Δk ↑ = k ↑ + k G} ↑ magnitude | k ↑ + k _G ↑ | is | k ↑ | / n _eff as is reciprocal lattice k _G ↑ is present becomes smaller, A two-dimensional lattice structure is formed.

  Here, the wave vector Δk ↑ represents a wave vector after the light having the wave vector k ↑ is diffracted in the light emitting photonic crystal structure (that is, the direction of the wave vector is changed).

  Thereby, the light amplified in the standing wave forming photonic crystal structure is diffracted in the light emitting photonic crystal structure, and the wave number vector Δk ↑ of the diffracted light exists in the light cone.

  Therefore, the light in the two-dimensional photonic crystal layer is emitted to the outside without causing total reflection at the interface between the two-dimensional photonic crystal layer and the outside, and a laser beam is obtained. At that time, the wave number component in the direction parallel to the two-dimensional photonic crystal layer is maintained at the interface. Therefore, when the wave vector magnitude | Δk ↑ | of the scattered light is 0, the laser beam is When emitted perpendicularly to the two-dimensional photonic crystal layer and | Δk ↑ | has a value other than 0, an inclined beam having an inclination angle corresponding to the magnitude and direction of the wave number vector Δk ↑ of the scattered light is obtained. .

  In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, the resonator lattice point 12A of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation is a rectangular lattice as shown in FIG. Placed in.

  Further, in the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, a schematic plane of the resonator lattice point 12A and the coupler lattice point 12C of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation. The configuration is expressed as shown in FIG.

  Further, a schematic cross-sectional structure taken along line VI-VI in FIG. 54 is represented as shown in FIG. 55A, and a schematic cross-sectional structure taken along line VII-VII in FIG. 54 is shown in FIG. Represented as shown.

As shown in FIG. 55A, the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment includes a standing wave forming photonic crystal layer 12 and a standing wave forming photonic crystal layer 12. Resonance of a rectangular lattice that is disposed inside and diffracts the light wave at the X-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 within the plane of the standing wave forming photonic crystal layer 12 A grating for a coupler that diffracts the light wave at the X-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 in the direction perpendicular to the plane of the standing wave forming photonic crystal layer 12 And a point 12C. Here, if the lattice constants of the rectangular lattice are a ₁ and a ₂ , one side a ₁ of the rectangular lattice is equal to ½ of the in-medium wavelength λ.

  In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, any lattice system can be considered for the coupler lattice point 12C, and the periods do not need to match. When the lattice system and the period of the coupler lattice point 12C are changed, the emission direction and angle are also changed.

In the two-dimensional photonic crystal surface-emitting laser according to the eighth embodiment, in a rectangular lattice of resonator grid points 12A, the lattice constant a ₁ is equal to 1/2 of the medium wavelength lambda, of a ₂ The range is not particularly limited. However, assuming a realistic structure,

0.5 × a ₁ <a ₂ <3 × a ₁ (5)

It is desirable that

  In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, the coupler lattice point 12C is arranged in the standing wave forming photonic crystal layer 12.

  In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, the resonator lattice point 12A and the coupler lattice point 12C of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation are shown in FIG. ) And as shown in FIG. 55 (b).

  In addition, the diameter and depth of the resonator lattice point 12A and the coupler lattice point 12C that are prototyped are about 120 nm and 115 nm, for example, and the pitch is about 280 nm, for example. These numerical examples can be appropriately changed depending on the material system constituting the substrate 10 and the active layer 14, the material system of the two-dimensional photonic crystal layer 12, the wavelength in the medium, and the like.

  For example, in the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment to which a GaAs / AlGaAs-based material is applied, the in-medium wavelength λ of the two-dimensional photonic crystal layer 12 is about 200 nm to about 300 nm. The output light wavelength is about 900 nm to about 915 nm.

  The resonator lattice points 12A and the coupler lattice points 12C may be filled with semiconductor layers having different refractive indexes, instead of being formed as air holes, for example. For example, the GaAs layer may be formed by filling an AlGaAs layer. For example, in the manufacturing process of fusing the two-dimensional photonic crystal layer 12, when the cavity shapes of the resonator lattice points 12A and the coupler lattice points 12C are deformed, the semiconductor layers having different refractive indexes may be filled. This is effective in avoiding such deformation.

  A schematic cross-sectional structure of the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment taken along line VI-VI in FIG. 54 is expressed as shown in FIG. 56A, and VII-VII in FIG. A schematic cross-sectional structure of the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment along the line is expressed as shown in FIG.

  That is, the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment includes a substrate (24: FIG. 35), a first cladding layer 10 disposed on the substrate (24), and the first cladding layer 10 The standing clad layer-forming photonic crystal layer 12 includes a first clad layer 16 disposed thereon, and an active layer 14 sandwiched between the first clad layer 10 and the second clad layer 16. 10 and the active layer 14 may be disposed adjacent to each other in the direction perpendicular to the surface of the active layer 14. As shown in FIG. 41, a carrier block layer 13 is provided between the standing wave forming photonic crystal layer 12 and the active layer 14.

(Modification 1)
A schematic cross-sectional structure of a two-dimensional photonic crystal surface emitting laser according to Modification 1 of the eighth embodiment along the line VI-VI in FIG. 54 is expressed as shown in FIG. A schematic cross-sectional structure of a two-dimensional photonic crystal surface emitting laser according to Modification 1 of the eighth embodiment along the line VII-VII is expressed as shown in FIG.

  That is, in the two-dimensional photonic crystal surface emitting laser according to the first modification of the seventh embodiment, the standing wave forming photonic crystal layer 12 is as shown in FIGS. 57 (a) and 57 (b). In addition, the active layer 14 may be disposed adjacent to the second cladding layer 16 and the active layer 14 in the direction perpendicular to the plane. Although not shown in FIGS. 57 (a) and 57 (b), a carrier block is formed between the standing wave forming photonic crystal layer 12 and the active layer 14 as in FIG. The layer 13 may be disposed.

(Modification 2)
A schematic cross-sectional structure of a two-dimensional photonic crystal surface emitting laser according to Modification 2 of the eighth embodiment along the line VI-VI in FIG. 54 is expressed as shown in FIG.

In other words, the two-dimensional photonic crystal surface-emitting laser according to a second modification of the eighth embodiment, as shown in FIG. 58 (a), are laminated with the photonic crystal layer 12 ₁ for the standing wave formed The light emitting photonic crystal layer 12 ₂ may be further provided, and the coupler lattice point 12C may be disposed in the light emitting photonic crystal layer 12 ₂ .

The two-dimensional photonic crystal surface emitting laser according to the second modification of the eighth embodiment is disposed on the substrate (24: FIG. 35) and the substrate (24) as shown in FIG. 58 (a). The first clad layer 10, a second clad layer 16 disposed on the first clad layer 10, and an active layer 14 sandwiched between the first clad layer 10 and the second clad layer 16, and standing wave formation The photonic crystal layer 12 ₁ for light and the photonic crystal layer 12 ₂ for light emission sandwich the active layer 14 between the first cladding layer 10 and the second cladding layer 16 in the direction perpendicular to the surface of the active layer 14. Be placed.

Further, although not shown in FIG. 58 (a), between the standing wave forming photonic crystal layer 12 ₁ and the active layer 14 and between the light emitting photonic crystal layer 12 ₂ and the active layer 14. In the meantime, similarly to FIG. 56, the carrier block layers 13 may be arranged respectively.

Further, in FIG. 58A, the stacking order of the standing wave forming photonic crystal layer 12 ₁ and the light emitting photonic crystal layer 12 ₂ is reversed so that the active layer 14 and the second cladding layer 16 are disposed. the light-emitting photonic crystal layer 12 ₂ is arranged, it may be arranged a photo for the standing wave formed photonic crystal layer ₁₂₁ between the active layer 14 and the first cladding layer 10. Since the light emitting photonic crystal layer 12 ₂ where the coupler lattice point 12C is disposed can be disposed at a position close to the light extraction direction, the light extraction efficiency can be increased.

(Modification 3)
A schematic cross-sectional structure of a two-dimensional photonic crystal surface emitting laser according to Modification 3 of the eighth embodiment along the VI-VI line in FIG. 54 is expressed as shown in FIG.

That is, in the two-dimensional photonic crystal surface emitting laser according to the third modification of the eighth embodiment, the standing wave forming photonic crystal layer 12 ₁ and the light emitting photonic crystal layer 12 ₂ are the second The clad layer 16 and the active layer 14 may be disposed adjacent to each other in the direction perpendicular to the surface of the active layer 14. Further, although not shown in FIG. 58 (b), between the light-emitting photonic crystal layer 12 ₂ and the active layer 14, similarly to FIG. 56, be arranged carrier block layer 13 good.

In FIG. 58 (b), the standing wave forming photonic crystal layer 12 ₁ and the light emitting photonic crystal layer 12 ₂ are stacked in the reverse order, and the standing wave forming photonic crystal is formed on the active layer. The crystal layer 12 ₁ may be disposed, and the light emitting photonic crystal layer 12 ₂ may be disposed on the standing wave forming photonic crystal layer 12 ₁ . Better to place the active layer 14 positioned standing wave forming photonic crystal layer 12 ₁ close to it, the gain peak near the active layer 14, it becomes possible to superimpose the wavelength of resonant modes, standing waves formed The action can be carried out more effectively. Further, since the light emitting photonic crystal layer 12 ₂ where the coupler lattice point 12C is disposed can be disposed at a position close to the light extraction direction, the light extraction efficiency can be increased.

(Modification 4)
A schematic cross-sectional structure of a two-dimensional photonic crystal surface emitting laser according to Modification 4 of the eighth embodiment along the VI-VI line of FIG. 54 is represented as shown in FIG.

That is, in the two-dimensional photonic crystal surface emitting laser according to the fourth modification of the eighth embodiment, the standing wave forming photonic crystal layer 12 ₁ and the light emitting photonic crystal layer 12 ₂ have the first structure. The clad layer 10 and the active layer 14 may be disposed adjacent to each other in the direction perpendicular to the surface of the active layer 14. Further, although not shown in FIG. 58 (c), between the standing wave forming photonic crystal layer ₁₂₁ and the active layer 14, similarly to FIG. 56, to place the carrier block layer 13 May be.

In FIG. 58 (c), the stacking order of the standing wave forming photonic crystal layer 12 ₁ and the light emitting photonic crystal layer 12 ₂ is reversed, and the light emitting photonic is close to the active layer 14. the crystal layer 12 ₂ may be disposed. Since the light emitting photonic crystal layer 12 ₂ where the coupler lattice point 12C is disposed can be disposed at a position close to the light extraction direction, the light extraction efficiency can be increased.

(Modification 5)
Schematic illustration of resonator lattice points 12A and coupler lattice points 12C of a two-dimensional photonic crystal layer applied to X-point oscillation in a two-dimensional photonic crystal surface emitting laser according to Modification 5 of the eighth embodiment The planar configuration is expressed as shown in FIG. 59 (a), and is a band structure of a two-dimensional photonic crystal corresponding to FIG. 59 (a). The relationship between the normalized frequency (c / a) and the wave number is , As shown in FIG. 59 (b).

  The two-dimensional photonic crystal surface emitting laser according to the fifth modification of the eighth embodiment corresponds to the example of the rectangular lattice (X-point oscillation), and the standing wave forming photonic crystal layer 12 is used. The oscillation at the X-point band edge (near the R region in FIG. 59B) in the photonic band structure of FIG.

  As shown in FIGS. 59A and 59B, the two-dimensional photonic crystal surface emitting laser according to Modification 5 of the eighth embodiment includes a standing wave forming photonic crystal layer 12, The light wave at the X-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 is disposed in the standing wave forming photonic crystal layer 12, and A light wave at the X-point band edge in the photonic band structure of the resonator lattice point 12A to be diffracted in the plane and the standing wave forming photonic crystal layer 12 is perpendicular to the plane of the standing wave forming photonic crystal layer 12 A grating point 12C for a coupler to be diffracted into the same.

In the two-dimensional photonic crystal surface emitting laser according to the fifth modification of the eighth embodiment, the resonator lattice point 12A has _first lattice constants a ₁ and a ₂ as shown in FIG. 59 (a). The grid points 12C for the coupler are arranged in a second rectangular lattice different from the first rectangular lattice. Here, the lattice constants in the x and y directions of the second rectangular lattice are the in-medium wavelength 2a ₁ and the lattice constants a ₁ and a _{2 in} the x and y directions of the first rectangular lattice. equal to a ₂

  Other configurations are the same as those of the eighth embodiment and its modifications 1 to 4.

(Modification 6)
In the two-dimensional photonic crystal surface emitting laser according to the sixth modification of the eighth embodiment, the schematic plan configuration of the resonator lattice point 12A of the two-dimensional photonic crystal layer 12 applied to the X point oscillation is shown in FIG. As shown to 60 (a), it arrange | positions at a rhombus lattice. Moreover, it is the band structure of the two-dimensional photonic crystal corresponding to FIG. 60A, and the relationship between the normalized frequency (c / a) and the wave number is expressed as shown in FIG.

  The two-dimensional photonic crystal surface emitting laser according to the sixth modification of the eighth embodiment corresponds to the rhombus (X-point oscillation) example, and the standing wave forming photonic crystal layer 12 has The oscillation at the X point band edge (near the R region in FIG. 60B) in the photonic band structure is used.

  As shown in FIGS. 60A and 60B, the two-dimensional photonic crystal surface emitting laser according to Modification 6 of the eighth embodiment includes a standing wave forming photonic crystal layer 12, The light wave at the X-point band edge in the photonic band structure of the standing wave forming photonic crystal layer 12 is disposed in the standing wave forming photonic crystal layer 12, and A light wave at the X-point band edge in the photonic band structure of the resonator lattice point 12A to be diffracted in the plane and the standing wave forming photonic crystal layer 12 is perpendicular to the plane of the standing wave forming photonic crystal layer 12 A grating point 12C for a coupler to be diffracted into the same.

In the two-dimensional photonic crystal surface emitting laser according to the sixth modification of the eighth embodiment, the resonator lattice point 12A has a rhombic lattice having lattice constants a ₁ and a ₂ as shown in FIG. The coupler lattice points 12C are arranged in a rectangular lattice. Here, the lattice constant of the rectangular lattice is equal to the in-medium wavelengths λ and a ₂ with respect to the lattice constants a ₁ and a ₂ of the rhomboid lattice.

  Other configurations are the same as those of the eighth embodiment and its modifications 1 to 4.

  According to the eighth embodiment and its modifications 1 to 6, it is possible to provide a two-dimensional photonic crystal surface emitting laser that emits a line beam.

According to the eighth embodiment and its modifications 1 to 6, a two-dimensional photonic whose beam divergence angle can be controlled by the aspect ratio r (= a ₁ / a ₂ ) (r ≠ 1) of the rectangular lattice. A crystal surface emitting laser can be provided.

  According to the eighth embodiment and its modifications 1 to 6, it is possible to provide a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle.

(Control of beam divergence angle: resonator region RP and coupler region CP)
The resonator region RP, a region resonator grid point 12A is located in the standing wave forming photonic crystal layer 12, 12 _1, and the coupler region CP, the photonic crystal layer 12 for the standing wave formed Alternatively, this is a region where the coupler lattice point 12C is arranged in the light emitting photonic crystal layer 12 ₂ .

In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, the relationship between the width of the coupler region CP, the beam divergence angle, and the beam divergence region is schematically shown in FIGS. 11 (a) and 11 (b). And is expressed in the same manner as in FIG. That is, the width A ₁ of the coupler region CP _1, an example of beam spread angle theta _1, and the beam divergence region 30 ₁ is represented in the same manner as FIG. 11 (a), the width A ₂ of the coupler region CP _2, the beam divergence angle theta _2, and examples of beam spread region 30 ₂ is represented in the same manner as FIG. 11 (b), the width a ₃ coupler region CP _3, an example of beam spread angle theta _3, and beam spread region 30 ₃ Figure 11 (c ). Here, the magnitude relation of the width of the coupler region is A ₁ <A ₂ <A ₃ , the size of the coupler region CP ₁ is relatively small, and the size of the coupler region CP ₃ is relatively large. Further, the magnitude relation between the beam divergence angles that define the beam divergence areas 30 ₁ , 30 _2, and 30 ₃ is such that θ ₁ > θ ₂ > θ ₃ .

In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, the size relationship of the resonator region RP corresponding to FIG. 11A, FIG. 11B, and FIG. It is expressed in the same manner as in a), and the magnitude relationship between the beam divergence angles is expressed in the same manner as in FIG. That is, the larger the size of the resonator region RP, the smaller the beam divergence angle θ ₀ .

In the two-dimensional photonic crystal surface emitting laser according to the comparative example, it is a diagram showing the relationship of the size of the resonator region RP of the two-dimensional photonic crystal layer applied to square lattice Γ point oscillation, and is an example of RP ₁ Is represented in the same manner as in FIG. 13A, an example of RP ₂ is represented in the same manner as in FIG. 13B, and an example of RP ₃ is represented in the same manner as in FIG.

On the other hand, in the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, the relationship between the sizes of the resonator region RP and the coupler region CP of the two-dimensional photonic crystal layer applied to the X-point oscillation is shown. Examples of RP ₁ and CP ₁ are represented in the same manner as in FIG. 14A, examples of RP ₂ and CP ₂ are represented in the same manner as in FIG. 14B, and examples of RP ₃ and CP ₃ are illustrated in FIG. 14 (c).

To oscillate a two-dimensional photonic crystal surface emitting laser, a resonator region of a certain level or more is required. For square lattice Γ point oscillation of the comparative example therefore, an attempt to increase the beam divergence angle theta _0, can not be ensured that the resonator region RP _A required oscillation. That is, in the two-dimensional photonic crystal surface-emitting laser according to comparative example, in order to utilize the oscillation square lattice Γ point, since equal to the size of the size as a coupler region CP of the resonator region RP, the beam divergence angle theta ₀ When the size of the resonator region RP is reduced in order to increase the size, the resonator region RP necessary for oscillation is within the range of RP <RP _A in the size relationship of the resonator region RP as shown in FIG. _{Since A} cannot be secured, it cannot oscillate.

(Positioning relationship between coupler and resonator)
In the two-dimensional photonic crystal surface emitting laser according to the fifth modification of the eighth embodiment, the resonator grating in the resonator region RP and the coupler region CP of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation An example of the arrangement of the points 12A and the coupler lattice points 12C is expressed as shown in FIG.

Further, in the two-dimensional photonic crystal surface-emitting laser according to a fifth modification of the eighth embodiment, an example of arranging the coupler lattice point 12C to the light-emitting photonic crystal layer 12 _2, FIG. 62 (a) It is expressed as shown in Here, the pitch of the lattice points 12C for the coupler is the horizontal direction 2a ₁ and the vertical direction a ₂ . Examples of arranging the resonator grid point 12A on the standing wave formed photonic crystal layer 12 ₁ is expressed as shown in FIG. 62 (b). Here, the in-medium wavelength λ is equal to 2a ₁ . Further, an example in which the resonator lattice points 12A and the coupler lattice points 12C are arranged on the same photonic crystal layer 12 is represented as shown in FIG. Another example in which the point 12A and the coupler lattice point 12C are arranged is expressed as shown in FIG. 62 (d), and the resonator lattice point 12A and the coupler lattice point 12C are arranged in the same photonic crystal layer 12. Yet another example is represented as shown in FIG. Another example in which the resonator lattice points 12A and the coupler lattice points 12C are arranged on the same photonic crystal layer 12 is expressed as shown in FIG. FIG. 62F is a generalized example. Here, the coupler lattice points 12C can be arbitrarily arranged, and the pitch of the coupler lattice points 12C is, for example, the horizontal direction a ₃ = r ₁ a ₁ is represented by the vertical direction a ₄ = r ₂ a ₂ (r ₁ ≠ 1, r ₂ ≠ 1).

  In the two-dimensional photonic crystal surface emitting laser according to the fifth modification of the eighth embodiment, the positional relationship between the coupler lattice point 12C and the resonator lattice point 12A is shown in FIGS. 62 (c) to 62 (f). It can be set freely as shown. The LD characteristics (output, threshold value, etc.) vary depending on the arrangement relationship between the coupler lattice point 12C and the resonator lattice point 12A.

  The example of FIGS. 61 and 62 is an example of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation, and is applied to the two-dimensional photonic crystal surface emitting laser according to the fifth modification of the eighth embodiment. Although it corresponds, it can be similarly applied to other eighth embodiments.

(Beam divergence angle control by coupler arrangement)
In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, the NFP in the case where the sizes of the resonator region RP and the coupler region CP of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation are substantially equal Is represented as shown in FIG. 63 (a), and the beam expansion region 30 from the coupler region CP is represented as shown in FIG. 63 (b), and the resonator region RP corresponding to FIG. 63 (a) and An arrangement example of the resonator lattice points 12A and the coupler lattice points 12C in the coupler region CP is expressed as shown in FIG.

  In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, the size of the resonator region RP and the coupler region CP of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation is different. NFP is expressed as shown in FIG. 64A, and the beam expansion region 30 from the coupler region CP is expressed as shown in FIG. 64B, and the resonator region RP corresponding to FIG. 64A. An arrangement example of the resonator lattice point 12A and the coupler lattice point 12C in the coupler region CP is expressed as shown in FIG.

That is, in the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, the resonator and the coupler can be designed separately, and stable oscillation can be maintained by changing only the coupler arrangement. However, the beam divergence angle θ ₀ of the surface emitting laser light can be variously changed.

In the two-dimensional photonic crystal surface emitting laser according to the eighth embodiment, the coupler in which the coupler lattice point 12C is disposed while maintaining the size of the resonator region RP in which the resonator lattice point 12A is disposed. By changing the region CP, the beam divergence angle θ ₀ of the laser beam can be adjusted while maintaining stable oscillation.

(Relationship between the diameter D _c of the diameter D _r and couplers lattice point 12C of the resonator grid points 12A)
FIG. 65A shows an arrangement example in which the diameter D _r of the resonator lattice point 12A and the diameter D _c of the coupler lattice point 12C are different and arranged at the same point with D _c ≦ D _r . An example of being arranged at the same point with D _c > D _r is represented as shown in FIG.

Oscillation even when the relationship between a diameter D _c of the diameter D _r and couplers lattice point 12C of the resonator grid points 12A is what is available. However, as shown in FIG. 65A, when D _c ≦ D _r and the hole of the coupler lattice point 12C completely overlaps the hole of the resonator lattice point 12A, resonance occurs inside the laser. However, it cannot function as a laser diode because light cannot be extracted.

Further, as shown in FIG. 65B, the resonator lattice point 12A and the coupler lattice point 12C have a circular shape, and the diameter D _c of the coupler lattice point 12C is the diameter D _r of the resonator lattice point 12A. It may be formed larger than.

  On the other hand, when the coupler lattice point 12C and the resonator lattice point 12A are formed in different two-dimensional photonic crystal layers, there is no limitation.

  In the two-dimensional photonic crystal surface emitting lasers according to the seventh to eighth embodiments, the resonator lattice point 12A and the coupler lattice point 12C have arbitrary shapes, and the coupler lattice point 12C is the resonator lattice point. It may be formed larger than 12A.

FIG. 65A and FIG. 65B are examples of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation, and the two-dimensional photonic crystal according to the fifth modification of the eighth embodiment. Although correspond to the surface-emitting laser, the relationship of the diameter D _c of the diameter D _r and couplers lattice point 12C of the resonator grid points 12A, a similar relationship holds also in the implementation of other eighth.

(Shape of grid points (holes))
FIG. 66A shows an arrangement example in which the shape of the resonator lattice point 12A is different from the shape of the coupler lattice point 12C, where the resonator lattice point 12A has a circular shape and the coupler lattice point 12C has a triangular shape. 66), an example in which the resonator lattice point 12A has a rhombus shape and the coupler lattice point 12C has an oval shape is represented as shown in FIG. 66 (b).

  The resonator lattice point 12A and the coupler lattice point 12C may have a polygonal shape, a circular shape, an elliptical shape, or an oval shape. Here, the polygon includes a triangle, a quadrangle, a pentagon, a hexagon, an octagon, and the like.

  Further, the shape of the lattice point may be different between the coupler lattice point 12C and the resonator lattice point 12A as described below. Moreover, the direction of the shape of the lattice points may be inclined. When the direction of the shape of the lattice point is inclined, the laser output characteristic is affected, for example, the laser beam is output in an oblique direction.

  66 (a) and 66 (b) are examples of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation, and the two-dimensional photonic crystal according to the fifth modification of the eighth embodiment. Although it corresponds to a surface emitting laser, the relationship of the shape of the (hole) between the resonator lattice point 12A and the coupler lattice point 12C is the same in other eighth embodiments.

  As described above, according to the present invention, a two-dimensional photonic crystal surface emitting laser capable of controlling the beam divergence angle of a laser beam can be provided.

[Ninth embodiment]
(Element structure)
A schematic bird's-eye view structure of a two-dimensional photonic crystal surface emitting laser according to the ninth embodiment is arranged in a photonic crystal layer 12 and a photonic crystal layer 12 as shown in FIG. A resonance state forming lattice point 12 </ b> A that diffracts the light wave at the band edge in the photonic band structure of the layer 12 in the plane of the photonic crystal layer 12 and diffracts in the direction perpendicular to the plane of the photonic crystal layer 12 is provided.

  Here, a perturbation for diffracting the light wave in the direction perpendicular to the plane of the photonic crystal layer 12 is applied to the resonance state forming lattice point 12A. The resonance state forming lattice point 12A to which the perturbation is applied is represented by a perturbation state forming lattice point 12P. The perturbation state forming lattice point 12 </ b> P is disposed in the photonic crystal layer 12.

  Here, “perturbation” means that modulation is periodically applied to the resonance state forming lattice points 12 A that form a periodic structure in the photonic crystal layer 12. Further, the periodic modulation may be refractive index modulation, for example. Further, the periodic modulation may be, for example, hole size modulation. Further, the periodic modulation may be, for example, hole depth modulation. The periodic modulation may be, for example, both hole depth modulation and hole depth modulation.

  Theoretically, it is desirable to perturb the “refractive index” of the resonance state forming lattice point 12 </ b> A formed in the photonic crystal layer 12. Further, the same effect can be obtained by perturbing “hole size”, “hole depth”, or both.

In the example shown in FIG. 67, perturbation state forming lattice points 12P ₁ , 12P ₂ , 12P ₃ ... Periodically arranged in the y-axis direction of a rectangular lattice having lattice constants (a ₁ , a ₂ ). On the other hand, a perturbation of refractive index modulation is added.

  In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a square lattice, a rectangular lattice, a face-centered rectangular lattice, a triangular lattice, or the like can be applied as the lattice type of the resonance state forming lattice point 12A. It is.

  In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, various band edges are obtained by perturbing the resonance state forming lattice points 12A that form the periodic structure in the photonic crystal layer 12. Oscillation can be realized. For example, Γ point / X point / M point oscillation can be realized in a square lattice and a rectangular lattice, and Γ point / X point / J point oscillation can be realized in a face centered rectangular lattice and a triangular lattice.

  As shown in FIG. 67, the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment includes a substrate 24, a first cladding layer 10 disposed on the substrate 24, and a first cladding layer 10. The second clad layer 16 disposed, and the active layer 14 sandwiched between the first clad layer 10 and the second clad layer 16 are provided. Here, the first cladding layer 10 may be a p-type semiconductor layer, and the second cladding layer 16 may be an n-type semiconductor layer, or the conductivity may be reversed.

  Furthermore, the two-dimensional photonic crystal surface emitting laser according to the embodiment is disposed in a contact layer 18 disposed on the second cladding layer 16 and a surface emitting region on the contact layer 18 as shown in FIG. , A window layer 20 for extracting laser light, a window-like upper electrode 22 disposed on the window layer 20, and a lower electrode 26 disposed on the back surface of the substrate 24.

  As shown in FIG. 67, the photonic crystal layer 12 may be disposed between the first cladding layer 10 and the second cladding layer 16 and adjacent to the active layer 14 in the direction perpendicular to the surface of the active layer 14. good. Here, the active layer 14 may be formed of, for example, a multiple quantum well (MQW) layer.

  The photonic crystal layer 12 may be disposed between the first cladding layer 10 and the active layer 14 as shown in FIG.

  Further, as shown in FIG. 67, a carrier block layer 13 is provided between the active layer 14 and the photonic crystal layer 12, and carriers are effectively taken into the active layer 14 composed of the MQW layer and from the active layer 14. The inflow of carriers into the photonic crystal layer 12 may be blocked.

  The photonic crystal layer 12 may be disposed between the second cladding layer 16 and the active layer 14.

  As a material system of the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, for example, the following can be applied. That is, for example, at a wavelength of 1.3 μm to 1.5 μm, a GaInAsP / InP system, an infrared light with a wavelength of 900 nm is an InGaAs / GaAs system, and an infrared light / near infrared light with a wavelength of 800 nm to 900 is GaAlAs / GaAs. GaAlInAs / GaAs system, GaAlInAs / InP system for wavelengths of 1.3 μm to 1.67 μm, AlGaInP / GaAs system for wavelengths of 0.65 μm, GaInN / GaN system for blue light, etc. are applicable.

The real space of the rectangular lattice of the two-dimensional photonic crystal layer 12 applied to the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment is expressed as shown in FIG. The wave number space corresponding to the Fourier transform of the real space in (a) is expressed as shown in FIG. The lattice constant of the rectangular lattice is represented by (a ₁ , a ₂ ) as shown in FIG. 68 (a), and the reciprocal lattice constant is (b ₁ , b ₂ ) as shown in FIG. 68 (b). ). The diffraction vector k _{d at the} reciprocal lattice point is expressed as shown in FIG.

(Principle of surface light emission)
The principle of surface emission of a two-dimensional photonic crystal surface emitting laser will be described by taking as an example the case where the two-dimensional photonic crystal layer 12 has lattice points of a rectangular lattice.

In the two-dimensional photonic crystal surface emitting laser, an explanatory diagram in real space of the in-plane resonance state of the rectangular lattice of the two-dimensional photonic crystal layer 12 is expressed as shown in FIG. ) In the wave number space is represented as shown in FIG. 69 (b). Here, in the example shown in FIG. 69A, one side a ₂ of the rectangular lattice is equal to ½ of the in-medium wavelength λ. In the in-plane resonance state shown in FIG. 69 (a), the wave vector k _f ↑ is expressed as shown in FIG. 69 (b).

In-plane resonance state corresponding to FIG. 69, illustrating the wave number space k _x -k _y diffraction operation in the upward direction (z-axis direction) is expressed as shown in FIG. 70 (a), FIG. 70 ( illustration in wavenumber space k _z -k _y corresponding to a) is expressed as shown in FIG. 70 (b). Wave vector k _f ↑ the diffraction vector k _d ↑ is the wave number space k _x -k _y, as shown in FIG. 70 (a), the difference | k _f -k _d | has, in correspondence with the difference The surface emitting laser light can be emitted in the vector k _u ↑ direction inclined by the beam emission angle θ from the z axis on the wave number space k _y -k _z plane.

(Comparative example)
In the two-dimensional photonic crystal surface emitting laser according to the comparative example, an example of the real space arrangement of the resonance state forming lattice points 12A (square lattice) of the two-dimensional photonic crystal layer 12 is shown in FIG. 71 (a). An example of the real space arrangement of the light extraction lattice points 12C of the two-dimensional photonic crystal layer 12 is expressed as shown in FIG. Furthermore, an example of real space arrangement in which the resonance state forming lattice points 12A and the light extraction lattice points 12C of the two-dimensional photonic crystal layer 12 are coupled is expressed as shown in FIG. 71 (c).

  The wave number space corresponding to FIG. 71 (a) is represented as shown in FIG. 71 (d), and the wave number space corresponding to FIG. 71 (c) is represented as shown in FIG. 71 (e). .

  The light extraction lattice point 12C is disposed in the same plane as the resonance state forming lattice point 12A, and has a structure with a different period from the basic structure of the resonance state forming lattice point 12A.

When the dielectric constant of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12 is ε _0.a (r ↑) and the dielectric constant of the light extraction lattice point 12C is ε _{1.a ′} (r ↑), The dielectric constant ε (r ↑) obtained by coupling the resonance state forming lattice point 12A and the light extraction lattice point 12C is

ε (r ↑) = ε _0.a (r ↑) + ε _{1.a ′} (r ↑) (6)

It is represented by In addition, since the dielectric constant ε (r ↑) has a periodic structure,

ε _a (r ↑) = ε _a (r ↑ + a ↑) (7)

It is represented by Here, | a ↑ | represents a period related to the lattice constant.

  In the comparative example, the resonance state forming lattice point 12A and the light extraction lattice point 12C, such as an X point resonator, are used as separate lattices, and the light extraction lattice point 12C greatly affects the formation of the resonance state. For example, by introducing the light extraction lattice point 12C, unnecessary scattering or an unintended resonance mode occurs.

(Introduction of perturbation)
Therefore, in the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a perturbation is applied to the resonance state forming lattice point 12A as a method of extracting light without using the light extracting lattice. Obviously, the introduction of the perturbation has little influence on the formation of the resonance state compared to a structure in which another lattice is newly stacked.

  In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, an example of the real space arrangement of the resonance state forming lattice points (rectangular lattice) 12A of the two-dimensional photonic crystal layer 12 is shown in FIG. FIG. 72 is a conceptual diagram illustrating a state in which a perturbation of a sinusoidal function is applied to the resonance state forming lattice point (rectangular lattice) 12A of the two-dimensional photonic crystal layer 12 in the y-axis direction. It is expressed as shown in b). Further, a conceptual diagram for explaining the perturbation of the hole shape (hole diameter) modulation of the sine wave function in the y-axis direction in the resonance state forming lattice point (rectangular lattice) is shown in FIG. 72 (c). Is done.

Further, the wave number space corresponding to the Fourier transform of the real space in FIG. 72 (a) is represented as shown in FIG. 73 (a), and the wave number space corresponding to the Fourier transform of the real space in FIG. It is expressed as shown in FIG. The wave vector k _f ↑ and the diffraction vector k _d ↑ are as shown in FIGS. 73 (a) and 73 (b).

The dielectric of a perturbation term obtained by adding a perturbation of a sinusoidal function to the resonance state forming lattice point 12A with respect to the dielectric constant ε _0.a (r ↑) of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12. The rate can be expressed as ε ₁ (r ↑) sin (k _d ↑ · r ↑).

Therefore, the dielectric constant ε ^′ (r ↑) of the lattice point 12P for perturbation state formation obtained by adding the perturbation of the sinusoidal function to the basic structure of the lattice point 12A for resonance state formation of the two-dimensional photonic crystal layer 12 is

ε ^′ (r ↑) = ε _{0, a} (r ↑) + ε _{1, a} (r ↑) sin (k _d ↑ · r ↑) (8)

It is represented by To further generalize,

ε ^′ (r ↑) = ε _{0, a} (r ↑) + Σ _i ε _{i, a} (r ↑) sin (k _{d, i} ↑ · r ↑) (8a)

It is represented by As is apparent from the equation (8a), when a plurality of perturbations of a sinusoidal function are added to the basic structure of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12 in an arbitrary direction, Is established.

  In the comparative example, the resonance state forming lattice point 12A and the light extraction lattice point 12C, such as an X point resonator, are used as separate lattices, but the two-dimensional photonic crystal surface light emission according to the ninth embodiment is used. In the laser, a surface emitting laser can be realized with a simple structure by introducing a perturbation to the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12. Compared to the comparative example using two types of lattice points, only one type of resonance state forming lattice point 12A is provided, and therefore, the manufacture is also simplified.

  In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, as the crystal lattice of the two-dimensional photonic crystal layer 12, the refractive index, size, and size of the resonance state forming lattice point 12A that forms a periodic structure, Alternatively, since a structure in which perturbation is added to the depth is provided, the structure can be more easily manufactured and a stable resonance state can be formed.

(Refractive index modulation)
In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a perturbation of the refractive index modulation of a sinusoidal function is applied to the resonance state forming lattice point (rectangular lattice) 12A of the two-dimensional photonic crystal layer 12. An example of a real space arrangement for explaining the situation is represented as shown in FIG. In FIG. 74, a periodic refractive index modulation perturbation of a sinusoidal function is applied to the array lines PL ₁ , PL ₂ , PL ₃ . For example, a perturbation state forming lattice point 12P ₁ to which a perturbation of the refractive index n1 is added is arranged on the array line PL ₁ . Similarly, arranged on the line PL ₂ is disposed perturbed form lattice points 12P ₂ perturbations is applied having a refractive index of n2, perturbed formation perturbation is applied to the refractive index n3 is formed on alignment line PL ₃ A grid point 12P ₃ is arranged.

Since the square of the refractive index n corresponds to the dielectric constant ε, in the example shown in FIG. 74, the dielectric constant is periodically modulated in the repetition direction perpendicular to the array lines PL ₁ , PL ₂ , PL ₃ . The perturbation of is added.

The dielectric of a perturbation term obtained by adding a perturbation of a sinusoidal function to the resonance state forming lattice point 12A with respect to the dielectric constant ε _0.a (r ↑) of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12. The rate can be expressed as ε _{1, a} (r ↑) sin (k _d ↑ · r ↑).

Therefore, the dielectric constant ε _a ^′ (perturbation state forming lattice point 12P obtained by adding a periodic refractive index modulation perturbation of a sinusoidal function to the basic structure of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12. r ↑)

ε _a ^′ (r ↑) = ε _{0, a} (r ↑) + ε _{1, a} (r ↑) sin (k _d ↑ · r ↑) (9)

It is represented by In the example of FIG. 74, the vector r ↑ in the equation (9) corresponds to a vector in the vertical direction with respect to the array lines PL ₁ , PL ₂ , PL ₃ .

(Pole shape (hole diameter) modulation)
In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a hole shape (hole diameter) modulation of a sinusoidal function is applied to a resonance state forming lattice point (rectangular lattice) 12A of the two-dimensional photonic crystal layer 12. An example of a real space arrangement for explaining how the perturbation is applied is expressed as shown in FIG. In FIG. 75, a periodic hole shape (hole diameter) modulation perturbation of a sine wave function is applied to the array lines PL ₁ , PL ₂ , PL ₃ . For example, the perturbation state forming lattice point 12P ₁ to which the perturbation of the hole diameter D1 is added is arranged on the array line PL ₁ . Similarly, sequence line on PL ₂ is arranged perturbed form lattice points 12P ₂ perturbations were added a pore size D2, perturbed forming lattice perturbation is applied with a pore diameter D3 is on alignment line PL ₃ Point 12P ₃ is arranged.

The _hole diameter of the perturbation term obtained by adding a perturbation of a sinusoidal function to the resonance state forming lattice point 12A with respect to the _hole diameter d _0.a (r ↑) of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12 is , D _{1, a} (r ↑) sin (k _d ↑ · r ↑).

Therefore, the hole diameter d _{a of} the perturbation state forming lattice point 12P obtained by adding a perturbation of periodic hole shape (hole diameter) modulation of a sinusoidal function to the basic structure of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12. (R ↑)

d _a (r ↑) = d _{0, a} (r ↑) + d _{1, a} (r ↑) sin (k _d ↑ · r ↑) (10)

It is represented by In the example of FIG. 75, the vector r ↑ in the equation (10) corresponds to a vector in the vertical direction with respect to the array lines PL ₁ , PL ₂ , PL ₃ .

(Depth depth modulation)
In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a perturbation of hole depth modulation is applied to a resonance state forming lattice point (rectangular lattice) 12A of the two-dimensional photonic crystal layer 12 A real space arrangement example to be described is represented as shown in FIG. In FIG. 76, periodic hole depth modulation perturbation of a sinusoidal function is applied to the array lines PL ₁ , PL ₂ , PL ₃ . For example, a perturbation state forming lattice point 12P ₁ to which a perturbation of depth H1 is added is arranged on the array line PL ₁ . Similarly, sequence line perturbation depth H2 is on PL ₂ is disposed perturbed form lattice points 12P ₂ made, perturbed formation perturbation is applied in sequence line PL ₃ deep on top of H3 A grid point 12P ₃ is arranged.

The depth of the perturbation term obtained by adding a perturbation of a sinusoidal function to the resonance state forming lattice point 12A with respect to the depth h _0.a (r ↑) of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12. The height can be expressed by h _{1, a} (r ↑) sin (k _d ↑ · r ↑).

Accordingly, the depth h _a (r of the perturbation state forming lattice point 12P obtained by adding a periodic depth modulation perturbation of a sinusoidal function to the basic structure of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12. ↑)

h _a (r ↑) = h _{0, a} (r ↑) + h _{1, a} (r ↑) sin (k _d ↑ · r ↑) (11)

It is represented by

(Perturbation of pore diameter d: rectangular lattice X point)
In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a hole shape (hole diameter) in the y-axis direction is formed at a resonance state forming lattice point (rectangular lattice X point) 12A of the two-dimensional photonic crystal layer 12. A real space arrangement example to which modulation perturbation is added is expressed as shown in FIG. 77, and the wave number space corresponding to the Fourier transform of FIG. 77 is expressed as shown in FIG.

Referring to the equation (10), a perturbation term obtained by adding a perturbation of a sinusoidal function to the resonance state forming lattice point 12A with respect to the hole diameter d ₀ of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12. Can be expressed by d ₁ sin (k _d ^' ↑ · r ↑).

That is, a perturbation state forming lattice point 12P obtained by adding a perturbation of periodic hole shape (hole diameter) modulation of a sinusoidal function in the y-axis direction to the basic structure of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12. The hole diameter d of is referred to the equation (10),

d = d ₀ + d ₁ sin (k _d ^' ↑ · r ↑) (12)

It is represented by In addition, k _d ^' ↑ ・ r ↑

^{_{k d '↑ · r ↑ =}} (k dx', k dy ') (ma x, ma y)
_{= (0, b y / 2} · s) (ma x, ma y) = πns (13)

It is represented by Here, a _x b _x = a _y b _y = 2π, and the following equation is established. That is,

d = d ₀ + d ₁ sin (πns) (14)

Thus, sinusoidal function sin [theta _d perturbation terms the beam emission angle of the medium as theta _d is

sin θ _d = Δk / k = (a _yc ⁻¹ −a _y ⁻¹ ) / a _y ⁻¹ = a _y / a _yc −1 = s−1 (15)

Here, s is referred to as a perturbation coefficient.

The perturbation coefficient s is expressed as a ratio (a _y / a _yc ) between the lattice constant a _y in the y-axis direction and the lattice constant a _yc corresponding to the modulation amount (b _y / 2 · s) in the y-axis direction.

Assuming that the refractive index in the medium is n _d and the beam emission angle in the atmosphere is θ _air , the product of the refractive index n _d in the medium and the sinusoidal function sinθ _d of the perturbation term is sinθ function in the atmosphere. Equal to _air . That is, the following equation is established.

n _d sinθ _d = sinθ _air (16)

θ _air = sin ⁻¹ (n _d sin θ _d ) = sin ⁻¹ (n _d (s−1)) (17)

In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a hole shape in the y-axis direction is formed in the resonance state forming lattice point (rectangular lattice X point) 12A of the two-dimensional photonic crystal layer 12 ( lattice constant (a _x when adding perturbation pore size) modulation, a _y), a pore diameter d _1, perturbation factor _{s (= a y / a yc} ), and the numerical results of the beam output angle θ is, FIG. 79 Represented as shown. The lattice constants (a _x , a _y ) are (270 nm, 280 nm), the pore diameter d ₀ of the basic lattice is 70 nm, and the modulation amplitude d ₁ is 4 nm. Sample 1 is an example in which the perturbation coefficient s = 0.96, and the beam emission angle θ · 2θ is 7.6 ° · 15.2 °. Sample 2 is an example with a perturbation coefficient s = 0.98, and the beam emission angle θ · 2θ is 3.8 ° · 7.6 °. Sample 3 is an example with perturbation coefficients s = 0.96 and 0.98, and the beam emission angles θ · 2θ are 7.6 ° · 15.2 ° and 3.8 ° · 7.6 °. Here, the beam emission angle θ is defined by a beam emission angle measured from the z-axis on the yz plane, as shown in FIG. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, the surface emitting laser beam actually emitted from the two-dimensional photonic crystal layer 12 is a beam emission measured from the z axis on the yz plane. The range is 2θ in the plus / minus direction of the angle θ.

  In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, the hole shape (hole diameter) is modulated in the y-axis direction at the resonance state forming lattice point (rectangular lattice X point) of the two-dimensional photonic crystal layer. FIG. 80 (a) shows the FFP and the beam exit angle 2θ when the perturbation coefficient is s = 0.96, and the perturbation coefficient s = 0.98. The FFP at the time and the beam emission angle 2θ are expressed as shown in FIG. 80B, and the FFP and the beam emission angle 2θ at the time of the perturbation coefficient s = 0.98 and 0.96 are shown in FIG. Represented as shown. The results of FIGS. 80A, 80B, and 80C correspond to Sample 1, Sample 2, and Sample 3 of FIG. 79, respectively.

  As shown in FIG. 80A, two FFPs corresponding to the sample 1 in FIG. 79 appear at the beam emission angle 2θ = 15.8 °.

  As shown in FIG. 80B, two FFPs corresponding to the sample 2 in FIG. 79 appear at the beam emission angle 2θ = 7.7 °.

  As shown in FIG. 80 (c), a total of four FFPs corresponding to the sample 3 in FIG. 79 appear at the beam emission angles 2θ = 7.6 ° and 15.4 °.

That is, the basic structure of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12 has a perturbation term d ₁ sin (πns ₁ ) and d of periodic hole shape (hole diameter) modulation of a sinusoidal function in the y-axis direction. _The hole diameter d of the perturbation state forming lattice point 12P to which ₂ sin (πns ₂ ) is added is expressed by referring to the equation (14).

d = d ₀ + d ₁ sin (πns ₁ ) + d ₂ sin (πns ₂ ) (18)

It is represented by Here, s ₁ and s ₂ are two perturbation coefficients corresponding to the sample 3 in FIG. In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, the perturbation state is formed by adding a plurality of perturbations in the y-axis direction to the basic structure of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12 The hole diameter d of the lattice point 12P for use is superposed.

  Similarly, in the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a perturbation state obtained by adding a plurality of perturbations to the basic structure of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12 The superposition of the arbitrary plurality of perturbation terms is also established for the forming lattice point 12P.

In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, the hole shape (hole diameter) modulation in the y-axis direction is applied to the resonance state forming lattice point (rectangular lattice) 12A of the two-dimensional photonic crystal layer 12. An example of a real space arrangement of the perturbation state forming lattice points 12P to which perturbation is added is expressed as shown in FIG. In FIG. 81, a perturbation of periodic hole shape (hole diameter) modulation of a sine wave function is applied in the y-axis direction perpendicular to the array lines PL ₁ , PL ₂ , PL ₃ .

For example, the hole diameter d of the perturbation state forming lattice point 12P ₁ arranged on the array line PL ₁ is:

d = 100 + 10sin (0.96π × 0) = 100 (19)

It is represented by Similarly, the hole diameter d of the perturbation state forming lattice point 12P ₂ arranged on the array line PL ₂ is:

d = 100 + 10sin (0.96π × 1) = 101.25 (20)

It is represented by Similarly, the hole diameter d of the perturbation state forming lattice point 12P ₃ arranged on the array line PL ₃ is:

d = 100 + 10sin (0.96π × 2) = 97.51 (21)

It is represented by

The beam emission angle θ _air in the atmosphere is

^{_{θ air = sin -1 (n d}} sinθ d) = sin -1 (n d (s-1))
= Sin ⁻¹ (3.3 (0.96-1)) = 7.6 ° (22)

Is obtained.

In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a hole shape (hole diameter) in the y-axis direction is formed in a resonance state forming lattice point (face-centered rectangular lattice) 12A of the two-dimensional photonic crystal layer 12. An example of the real space arrangement when modulation perturbation is applied is shown in FIG. In FIG. 82, a perturbation of periodic hole shape (hole diameter) modulation of a sinusoidal function is applied in the y-axis direction perpendicular to the array lines PL ₁ , PL ₂ , PL ₃ .

For example, the hole diameter d of the perturbation state forming lattice point 12P ₁ disposed on the array line PL ₁ is expressed in the same manner as the equation (19), and the perturbation state forming lattice point 12P disposed on the array line PL _2. The hole diameter d of ₂ is expressed in the same manner as in the equation (20), and the hole diameter d of the perturbation state forming lattice points 12P ₃ arranged on the array line PL ₃ is expressed in the same manner as in the equation (21).

In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, the perturbation of the hole shape (hole diameter) modulation in the y-axis direction is applied to the resonance state forming lattice point (square lattice) 12A of the two-dimensional photonic crystal layer. An example of real space arrangement when added is shown in FIG. 83, a perturbation of periodic hole shape (hole diameter) modulation of a sinusoidal function is applied in the y-axis direction perpendicular to the array lines PL ₁ , PL ₂ , PL ₃ .

For example, the hole diameter d of the perturbation state forming lattice point 12P ₁ disposed on the array line PL ₁ is expressed in the same manner as the equation (19), and the perturbation state forming lattice point 12P disposed on the array line PL _2. The hole diameter d of ₂ is expressed in the same manner as in the equation (20), and the hole diameter d of the perturbation state forming lattice points 12P ₃ arranged on the array line PL ₃ is expressed in the same manner as in the equation (21).

(Outgoing direction and FFP)
In the two-dimensional photonic crystal surface emitting laser according to the comparative example, for example, the FFP of the resonance state forming lattice point (square lattice Γ point) of the two-dimensional photonic crystal layer 12 is schematically represented as shown in FIG. Is done. That is, an FFP having a beam divergence angle θ ₀ is obtained from the z-axis direction perpendicular to the surface of the two-dimensional photonic crystal layer 12 disposed on the substrate 10 in the xyz three-dimensional space. Here, the FFP is a two-dimensionally small shape with a beam divergence angle θ ₀ of about 1 °. This is a result that arises in principle by taking out the resonance state forming lattice point (square lattice Γ point) of the two-dimensional photonic crystal layer 12 from the two-dimensional large-area oscillation in the direction perpendicular to the plane.

In the two-dimensional photonic crystal surface emitting laser according to the comparative example, the FFP of the resonance state forming lattice point (rectangular lattice Γ point) of the two-dimensional photonic crystal layer is schematically represented as shown in FIG. . That is, an FFP having a beam divergence angle θ ₀ is obtained from the z-axis direction perpendicular to the surface of the two-dimensional photonic crystal layer 12 disposed on the substrate 10 in the xyz three-dimensional space. Here, the FFP is a stripe or oval shape in the y-axis direction with a beam divergence angle θ ₀ of about 5 ° to about 20 °.

In the two-dimensional photonic crystal surface emitting laser according to the comparative example, the light extraction lattice point 12C is superimposed on the resonance state forming lattice point (square lattice M point) 12A of the two-dimensional photonic crystal layer 12 (FIG. 71). The FFP of the example shown is schematically represented as shown in FIG. That is, an FFP with a beam emission angle θ ₁₁ is obtained from the z-axis direction perpendicular to the surface of the two-dimensional photonic crystal layer 12 disposed on the substrate 10 in the xyz three-dimensional space. Here, the beam emission angle θ ₁₁ is freely set between 0 ° and 90 °. The outgoing beam has a spread width of a spread angle 2θ ₀ , but since the angle θ ₀ is about 1 °, the spread width is 2 as shown on the plane P _z parallel to the xy plane. Dimensionally small.

In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, when a perturbation is applied in the y-axis direction to the resonance state forming lattice point (rectangular lattice X point) of the two-dimensional photonic crystal layer 12 The FFP is schematically represented as shown in FIG. That is, an FFP with a beam emission angle θ ₂₂ is obtained from the z-axis direction perpendicular to the surface of the two-dimensional photonic crystal layer 12 disposed on the substrate 10 in the xyz three-dimensional space. The beam emission angle θ ₂₂ can be freely set between 0 ° and 90 °. Further, the outgoing beam has a spread width of a spread angle 2θ ₃ , but the angle θ ₃ is about 5 ° to about 20 °, and therefore, as shown on the plane P _z parallel to the xy plane, The spread width is relatively larger than that of the comparative example shown in FIG.

(Structure example of hole depth modulation)
In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a perturbation of hole depth modulation is applied to the lattice point (rectangular lattice) for forming the resonance state of the two-dimensional photonic crystal layer in the y-axis direction. A schematic planar pattern configuration of the perturbation state forming lattice points 12P is expressed as shown in FIG.

  Also, a schematic cross-sectional structure taken along line VIII-VIII in FIG. 88 (a) is represented as shown in FIG. 89 (a), and a schematic cross-sectional structure taken along line IX-IX in FIG. The schematic cross-sectional structure expressed as shown in b) and taken along line XX in FIG. 88 is expressed as shown in FIG.

As shown in FIG. 88 and FIG. 89, the hole depth of the perturbation state forming lattice point 12P ₁ is represented by H1 with respect to the hole depth h ₀ of the resonance state forming lattice point. The depth of the hole at the lattice point 12P ₂ is represented by H2, and the depth of the hole at the lattice point 12P ₃ for forming the perturbation state is represented by H3.

(Structural example of refractive index modulation)
In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a perturbation in which a perturbation of refractive index modulation is added in the y-axis direction to a resonance state forming lattice point (rectangular lattice) of the two-dimensional photonic crystal layer A schematic planar pattern configuration of the state forming lattice points 12P is expressed as shown in FIG.

  Also, an example of the refractive index distribution in the x-axis direction along the line XI-XI in FIG. 90 is expressed as shown in FIG. 91A, and an example of the refractive index distribution in the x-axis direction along the line XII-XII in FIG. Is represented as shown in FIG. 91 (b), and an example of the refractive index distribution in the x-axis direction along the line XIII-XIII in FIG. 90 is represented as shown in FIG. 91 (c).

As shown in FIGS. 90 and 91, the refractive index of the perturbation state forming lattice point 12P ₁ is represented by n ₁ with respect to the refractive index n ₀ in the medium of the two-dimensional photonic crystal layer 12, and the perturbation state formation is performed. The refractive index of the lattice point 12P ₂ for use is represented by n ₂ , and the refractive index of the perturbation state forming lattice point 12P ₃ is represented by n ₃ .

(Example of structure of hole shape (hole diameter) modulation)
In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, perturbation of the hole shape (hole diameter) modulation in the y-axis direction at the resonance state forming lattice point (rectangular lattice) of the two-dimensional photonic crystal layer 12 A schematic planar pattern configuration of the perturbation state forming lattice points 12P to which is added is expressed as shown in FIG.

  A schematic cross-sectional structure taken along line XIV-XIV in FIG. 92 is represented as shown in FIG. 93 (a), and a schematic cross-sectional structure taken along line XV-XV in FIG. 92 is shown in FIG. 93 (b). A schematic cross-sectional structure taken along line XVI-XVI of FIG. 92 is represented as shown in FIG.

As shown in FIGS. 92 and 93, a perturbation state forming lattice point 12P _{1 with} respect to the hole shape (hole diameter) d ₀ of the resonance state forming lattice point (rectangular lattice) 12A of the two-dimensional photonic crystal layer 12 is shown. is a pore diameter is represented by D1, the diameter of perturbed forming grid points 12P ₂ is represented by D2, the diameter of perturbed forming lattice points 12P ₃ is represented by D3.

  In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, a schematic plane configuration of the resonance state forming lattice points 12A of the two-dimensional photonic crystal layer 12 applied to the Γ-point oscillation (square lattice arrangement example) ) Is expressed as a band structure of a two-dimensional photonic crystal as shown in FIG. 94 (a), and the relationship between the normalized frequency [unit: c / a] and the wave vector is shown in FIG. 94 (b). Represented as shown.

  In the photonic band structure, a portion where the inclination is 0 is called a band edge. At the band edge, the group velocity of light becomes 0 and a standing wave is formed, so that the photonic crystal functions as a light resonator.

  The photonic crystal layer 12 is applied to diffraction in the direction perpendicular to the surface of the photonic crystal layer 12 by a perturbation state forming lattice point 12P obtained by perturbing the resonance state forming lattice point 12A.

  In the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, when the oscillation at the M-point band edge of the photonic band structure is used, the periodic structure of the photonic crystal has a function of forming a resonance state for oscillation. However, light can be extracted by providing the perturbation state forming lattice point 12P obtained by adding perturbation to the resonance state forming lattice point 12A.

  Moreover, the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment can operate in a large area and a stable single mode. That is, in the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment, the electromagnetic field distribution is generated by the resonance state forming lattice points 12A and the perturbation state forming lattice points 12P formed in the photonic crystal layer 12. Since it is defined, a single mode can be maintained even in a large area. For this reason, for example, processing such as focusing W-class output light on a small point via a lens is easy.

  For example, in FIG. 67, the size of the photonic crystal layer 12 is, for example, about 700 μm × about 700 μm.

  Further, in the example of a near field image (NFP), a large area oscillation of about 100 μm square to an ultra large area oscillation of about several hundred μm square can be realized. The oscillation spectrum is obtained, for example, at room temperature continuous oscillation at a wavelength of about 950 nm with a full width at half maximum (FWHM) of about 0.16 nm. Further, in a single mode, a light output of 2.7 W is obtained by pulse driving of 1 kHz-50 ns.

  For example, the resonance state forming lattice points 12A can be arranged at a pitch of about the period of light. For example, if the holes are filled with air, the air / semiconductor pitch can be arranged in a period of about 400 nm in the optical communication band, and can be arranged in a period of about 230 nm in blue light. .

  In addition, the diameter and depth of the resonant state forming lattice point 12A that has been experimentally manufactured are approximately 120 nm and 115 nm, for example, and the pitch is approximately 286 nm, for example. These numerical examples can be appropriately changed depending on the material system constituting the substrate 10 and the active layer 14, the material system of the two-dimensional photonic crystal layer 12, the wavelength in the medium, and the like.

  For example, in the two-dimensional photonic crystal surface emitting laser according to the ninth embodiment to which a GaAs / AlGaAs-based material is applied, the in-medium wavelength λ of the two-dimensional photonic crystal layer 12 is about 200 nm to about 300 nm. The output light wavelength is about 900 nm to about 915 nm.

In addition, when the refractive index modulation is performed on the perturbation state forming lattice points 12P, for example, semiconductor layers having different refractive indexes may be filled. For example, the GaAs layer may be formed by filling an Al _x Ga _1-x As layer in which the composition ratio x is modulated. For example, in the manufacturing process in which the two-dimensional photonic crystal layer 12 is fused, when the hole shape of the perturbation state forming lattice point 12P is deformed, filling with a semiconductor layer having a different refractive index may cause such deformation. It is effective in avoiding.

  According to the ninth embodiment, there is provided a two-dimensional photonic crystal surface emitting laser capable of controlling the beam emission angle, beam divergence angle, and shape of a laser beam while maintaining stable oscillation with a simple structure. be able to.

[Tenth embodiment]
A schematic bird's-eye view structure of the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment is expressed in the same manner as FIG.

  The two-dimensional photonic crystal surface emitting laser according to the tenth embodiment is arranged in the photonic crystal layer 12 and the photonic crystal layer 12 periodically, and has a photonic band structure band. Resonance state forming lattice points 12A for diffracting the light wave at the end in the plane of the photonic crystal layer 12 and the photonic crystal layer 12 of the photonic crystal layer 12 periodically arranged in the photonic crystal layer 12 A perturbation state forming lattice point 12P that diffracts the light wave at the end in the plane of the photonic crystal layer 12 and diffracts the light wave in the plane perpendicular to the photonic crystal layer 12 is provided.

  Here, a perturbation for diffracting the light wave in the direction perpendicular to the plane of the photonic crystal layer 12 is applied to a part of the resonance state forming lattice point 12A. That is, the perturbation state forming lattice point 12P is formed by adding a perturbation for diffracting a light wave in the direction perpendicular to the plane of the photonic crystal layer 12 to a part of the resonance state forming lattice point 12A.

  The resonance state forming lattice point 12A to which the perturbation is applied is represented by a perturbation state forming lattice point 12P. The perturbation state forming lattice point 12 </ b> P is disposed in the photonic crystal layer 12.

  The perturbation applied to the perturbation state forming lattice point is periodic modulation. The periodic modulation may be refractive index modulation, hole size modulation, or hole depth modulation. Further, the periodic modulation may be hole depth modulation and hole depth modulation.

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, a square lattice, a rectangular lattice, a face-centered rectangular lattice, a triangular lattice, or the like can be applied as the lattice type of the resonance state forming lattice point 12A. It is.

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, various band edges can be obtained by perturbing the resonance state forming lattice points 12A forming the periodic structure in the photonic crystal layer 12. Oscillation can be realized. For example, Γ point / X point / M point oscillation can be realized in a square lattice and a rectangular lattice, and Γ point / X point / J point oscillation can be realized in a face centered rectangular lattice and a triangular lattice.

  As in FIG. 67, the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment is disposed on the substrate 24, the first cladding layer 10 disposed on the substrate 24, and the first cladding layer 10. And the active layer 14 sandwiched between the first cladding layer 10 and the second cladding layer 16. Here, the first cladding layer 10 may be a p-type semiconductor layer, and the second cladding layer 16 may be an n-type semiconductor layer, or the conductivity may be reversed.

  Further, the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment is similar to FIG. 67 in that the contact layer 18 disposed on the second cladding layer 16 and the surface emitting region on the contact layer 18 are formed. A window layer 20 that is disposed and for extracting laser light, a window-shaped upper electrode 22 disposed on the window layer 20, and a lower electrode 26 disposed on the back surface of the substrate 24 are provided.

  As in FIG. 67, the photonic crystal layer 12 may be disposed between the first cladding layer 10 and the second cladding layer 16 and adjacent to the active layer 14 in the direction perpendicular to the surface of the active layer 14. . Here, the active layer 14 may be formed of, for example, an MQW layer.

  Further, the photonic crystal layer 12 may be disposed between the first cladding layer 10 and the active layer 14 as in FIG.

  Further, as shown in FIG. 67, a carrier block layer 13 is provided between the active layer 14 and the photonic crystal layer 12, and carriers are effectively taken into the active layer 14 composed of the MQW layer and from the active layer 14. The inflow of carriers into the photonic crystal layer 12 may be blocked.

  The photonic crystal layer 12 may be disposed between the second cladding layer 16 and the active layer 14.

(M point oscillation: square lattice)
In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, schematic diagrams of the resonance state forming lattice points 12A and the perturbation state forming lattice points 12P of the two-dimensional photonic crystal layer 12 applied to M-point oscillation The target plane configuration is expressed as shown in FIG. FIG. 95B shows the band structure of the two-dimensional photonic crystal corresponding to FIG. 95A, and the relationship between the normalized frequency and the wave number vector is expressed as shown in FIG.

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, a resonance that diffracts a light wave at the M-point band edge (near the Q region in FIG. 95B) in the photonic band structure of the photonic crystal layer 12 As shown in FIG. 95A, state forming lattice points 12A are arranged in a square lattice, and perturbed state forming lattice points 12P are face-centered square lattices having a lattice constant twice that of the square lattice. The diagonal pitch of the perturbation state forming lattice points 12P is equal to the in-medium wavelength λ of the photonic crystal layer 12.

(X point oscillation: square lattice)
In the oscillation at the band edge of the X point of the photonic band structure, the periodic structure of the photonic crystal has only an optical amplification function for oscillation, but in order to diffract light in the same plane as this periodic structure. By providing the periodic structure (perturbation state formation), light can be extracted.

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, schematic diagrams of the resonance state forming lattice points 12A and the perturbation state forming lattice points 12P of the two-dimensional photonic crystal layer 12 applied to the X point oscillation The target plane configuration is arranged in a square lattice as shown in FIG. Moreover, it is the band structure of the two-dimensional photonic crystal corresponding to FIG. 96 (a), and the relationship between the normalized frequency and the wave number vector is expressed as shown in FIG. 96 (b).

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, resonance that diffracts a light wave at the X-point band edge (near the R region in FIG. 96B) in the photonic band structure of the photonic crystal layer 12 As shown in FIG. 96A, the state forming lattice point 12A is arranged in the first square lattice, and the perturbation state forming lattice point 12P has a lattice constant that is twice the lattice constant of the first square lattice. The lattice constant of the lattice point 12P for forming the perturbation state arranged in the second square lattice is equal to the in-medium wavelength λ of the photonic crystal layer.

(X point oscillation: triangular lattice)
In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, schematic diagrams of the resonance state forming lattice points 12A and the perturbation state forming lattice points 12P of the two-dimensional photonic crystal layer 12 applied to the X point oscillation The target plane configuration is arranged in a triangular lattice as shown in FIG. Moreover, it is the band structure of the two-dimensional photonic crystal corresponding to FIG. 97 (a), and the relationship between the normalized frequency and the wave number vector is expressed as shown in FIG. 97 (b).

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, resonance that diffracts a light wave at the X-point band edge (near the R region in FIG. 97B) in the photonic band structure of the photonic crystal layer 12 As shown in FIG. 97A, the state forming lattice points 12A are arranged in the first triangular lattice, and the perturbation state forming lattice points 12P are the second triangles having a pitch twice the pitch of the first triangular lattice. The height in plan view of the second triangular lattice disposed on the lattice is equal to the in-medium wavelength λ of the photonic crystal layer 12.

(J point oscillation: triangular lattice)
In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, in the oscillation at the band edge of the point J of the photonic band structure, the periodic structure of the photonic crystal has only an optical amplification function for oscillation. However, light can be extracted by providing a periodic structure (perturbation state formation) for diffracting light in the same plane as this periodic structure.

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the resonance state forming lattice point 12A and the perturbation state forming lattice point 12P of the two-dimensional photonic crystal layer 12 applied to the J point oscillation are as follows: As shown in FIG. 98 (a), they are arranged in a triangular lattice. Moreover, it is the band structure of the two-dimensional photonic crystal corresponding to FIG. 98 (a), and the relationship between the normalized frequency and the wave number vector is expressed as shown in FIG. 98 (b).

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, resonance that diffracts a light wave at the J-point band edge (near the S region in FIG. 98B) in the photonic band structure of the photonic crystal layer 12 As shown in FIG. 98A, the state forming lattice points 12A are arranged in the first triangular lattice, and the perturbation state forming lattice points 12P are face-centered triangles having a pitch three times the pitch of the first triangular lattice. One side of the face-centered triangular lattice arranged in the lattice is equal to twice the in-medium wavelength λ of the photonic crystal layer 12.

(X point oscillation: rectangular lattice)
In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, a schematic plan configuration of a resonance state forming lattice point and a perturbation state forming lattice point of a two-dimensional photonic crystal layer applied to X-point oscillation Are arranged in a rectangular lattice (example of a ₁ > a ₂ ) as shown in FIG. Moreover, it is a band structure of the two-dimensional photonic crystal corresponding to FIG. 99A, and the relationship between the normalized frequency and the wave number vector is expressed as shown in FIG. 99B.

In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, resonance that diffracts a light wave at the X-point band edge (near the R region in FIG. 99B) in the photonic band structure of the photonic crystal layer 12 As shown in FIG. 99A, the state forming lattice point 12A is arranged in a first rectangular lattice having lattice constants a ₁ and a ₂ , and the perturbation state forming lattice point 12P has a first length. They are arranged in a second rectangular lattice different from the rectangular lattice. Here, the lattice constant of the second rectangular lattice is equal to the aspect ratio r = a ₁ / a ₂ (r ≠ 1) defined by the lattice constants a ₁ and a ₂ of the _first rectangular lattice. It is equal to r times the medium wavelength λ and the medium wavelength λ.

(X point oscillation: rhombus lattice)
In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, schematic diagrams of the resonance state forming lattice points 12A and the perturbation state forming lattice points 12P of the two-dimensional photonic crystal layer 12 applied to the X point oscillation The target plane configuration is arranged in a rhombus lattice as shown in FIG. Moreover, it is the band structure of the two-dimensional photonic crystal corresponding to FIG. 100A, and the relationship between the normalized frequency and the wave number vector is expressed as shown in FIG.

In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, a resonance that diffracts a light wave at the X-point band edge (near the R region in FIG. 100B) in the photonic band structure of the photonic crystal layer 12 As shown in FIG. 100A, state forming lattice points 12A are arranged in a face-centered rectangular lattice having lattice constants a ₁ and a ₂ , and perturbed state forming lattice points 12P are arranged in a rectangular lattice. Is done. Here, the lattice constant of the rectangular lattice is the in-medium wavelength λ with respect to the aspect ratio r = a ₁ / a ₂ (r ≠ 1) defined by the lattice constants a ₁ and a ₂ of the face-centered rectangular lattice. Is equal to r times and the in-medium wavelength λ.

(X point oscillation: rectangular lattice)
In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the resonance state forming lattice points 12A and the perturbation state forming lattice points 12P of the two-dimensional photonic crystal layer applied to the X point oscillation are schematically shown. The planar configuration is arranged in a rectangular lattice (example of a ₁ <a ₂ ) as shown in FIG. Moreover, it is the band structure of the two-dimensional photonic crystal corresponding to FIG. 101A, and the relationship between the normalized frequency and the wave number is expressed as shown in FIG.

In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, resonance that diffracts a light wave at the X-point band end (near the R region in FIG. 101B) in the photonic band structure of the photonic crystal layer 12 As shown in FIG. 101A, the state forming lattice point 12A is arranged in a first rectangular lattice having lattice constants a ₁ and a ₂ , and the perturbation state forming lattice point 12P has a first length. They are arranged in a second rectangular lattice different from the rectangular lattice. Here, the lattice constants in the x and y directions of the second rectangular lattice are a ₁ and the wavelength in the medium with respect to the lattice constants a ₁ and a _{2 in} the x and y directions of the first rectangular lattice. It is equal to λ (= 2a ₂ ).

(X point oscillation: rhombus lattice)
In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the schematic plan configuration of the resonance state forming lattice point 12A of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation is shown in FIG. As shown to a), it arrange | positions at a rhombus lattice. Further, it is a band structure of a two-dimensional photonic crystal corresponding to FIG. 102A, and the relationship between the normalized frequency and the wave number is expressed as shown in FIG.

In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, resonance that diffracts a light wave at the X-point band edge (near the R region in FIG. 102B) in the photonic band structure of the photonic crystal layer 12 As shown in FIG. 102A, the state forming lattice points 12A are arranged in a rhombus lattice having lattice constants a ₁ and a ₂ , and the perturbation state forming lattice points 12P are arranged in a rectangular lattice. Here, the lattice constant of the rectangular lattice is equal to the in-medium wavelength λa ₁ and the in-medium wavelength λ with respect to the lattice constants a ₁ and a ₂ of the rhombus lattice.

  Other configurations are the same as those of the ninth embodiment.

  According to the tenth embodiment, a two-dimensional photonic crystal surface emitting laser capable of controlling the beam emission angle, beam divergence angle, and shape of a laser beam while maintaining stable oscillation with a simple structure is provided. be able to.

(Control of beam divergence angle: resonator region RP and perturbation state formation region PP)
The resonator region RP is a region where the resonance state forming lattice points 12A are arranged in the photonic crystal layer 12, and the perturbation state forming region PP is the perturbation state forming lattice points 12P in the photonic crystal layer 12. This is the area to be placed.

In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the relationship among the width A of the perturbation state formation region PP, the beam expansion angle θ ₀ , and the beam expansion region 30 is schematically shown in FIG. 11 (b) and FIG. 11 (c). That is, examples of the width A _{1 of} the perturbation state formation region PP ₁ , the beam expansion angle θ _a , and the beam expansion region 30 ₁ are represented in the same manner as in FIG. 11A, and the width A _{2 of} the perturbation state formation region PP ₂ examples of beam spread angle theta _b, and the beam divergence region 30 ₂ is represented in the same manner as FIG. 11 (b), the width a ₃ perturbation state formation region PP _3, the beam divergence angle theta _c, and beam spread region 30 ₃ An example is expressed similarly to FIG. Here, the beam divergence angles θ ₁ , θ ₂ , and θ ₃ in FIGS. 11A, 11B, and 11C are set to θ _a , θ _b , and θ _c . Further, the width relationship of the perturbation state formation region is A ₁ <A ₂ <A ₃ , the size of the perturbation state formation region PP ₁ is relatively small, and the size of the perturbation state formation region PP ₃ is relative. It ’s big. Further, the relationship between the beam divergence angles that define the beam divergence regions 30 ₁ , 30 _2, and 30 ₃ is such that θ _a > θ _b > θ _c .

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the magnitude relationship of the resonator region RP corresponding to FIG. 11A, FIG. 11B, and FIG. It is expressed in the same manner as in a), and the magnitude relationship between the beam divergence angles is expressed in the same manner as in FIG. In other words, the larger the size of the resonator region RP, the smaller the beam divergence angle.

In the two-dimensional photonic crystal surface emitting laser according to the comparative example, it is a diagram showing the relationship of the size of the resonator region RP of the two-dimensional photonic crystal layer applied to square lattice Γ point oscillation, and is an example of RP ₁ Is represented in the same manner as in FIG. 13A, an example of RP ₂ is represented in the same manner as in FIG. 13B, and an example of RP ₃ is represented in the same manner as in FIG.

On the other hand, in the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the relationship between the size of the resonator region RP and the perturbation state formation region PP of the two-dimensional photonic crystal layer applied to the X-point oscillation is shown. In the figure, examples of RP ₁ and PP ₁ are represented as shown in FIG. 14A, examples of RP ₂ and PP ₂ are represented as shown in FIG. 14B, and RP ₃ , PP 1 The example of ₃ is expressed as shown in FIG.

To oscillate a two-dimensional photonic crystal surface emitting laser, a resonator region of a certain level or more is required. For square lattice Γ point oscillation of the comparative example therefore, an attempt to increase the beam divergence angle theta _0, can not be ensured that the resonator region RP _A required oscillation. That is, in the two-dimensional photonic crystal surface emitting laser according to the comparative example, since the square lattice Γ point oscillation is used, the size of the resonator region RP is directly equal to the size of the perturbation state formation region PP. _When the size of the resonator region RP is reduced in order to increase ₀ , as shown in FIG. 12A, the resonator required for oscillation is within the range of RP <RP _A in the size relationship of the resonator region RP. since the region RP _A can not be secured, it is impossible to oscillate.

(Perturbation state formation and resonator arrangement)
In the two-dimensional photonic crystal surface emitting laser according to the fifth modification of the tenth embodiment, resonance in the resonator region RP and the perturbation state forming region PP of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation An arrangement example of the state forming lattice point 12A and the perturbation state forming lattice point 12P is expressed as shown in FIG.

Further, in the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, an example in which the resonance state forming lattice points 12A are arranged in the photonic crystal layer 12 is expressed as shown in FIG. The Here, the in-medium wavelength λ is equal to 2a ₂ . An example in which the resonance state forming lattice points 12A and the perturbation state forming lattice points 12P are arranged in the same photonic crystal layer 12 is expressed as shown in FIG.

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the arrangement relationship between the perturbation state forming lattice point 12P and the resonance state forming lattice point 12A can be freely set. The LD characteristics (output, threshold, etc.) vary depending on the arrangement relationship between the perturbation state forming lattice point 12P and the resonance state forming lattice point 12A.

  The example of FIGS. 103 and 104 is an example of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation, and corresponds to the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment. .

(Beam divergence angle control by perturbation state formation region PP)
In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, when the sizes of the resonator region RP and the perturbation state formation region PP of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation are substantially equal The NFP is expressed as shown in FIG. 105 (a), and the beam expansion region 30 from the perturbation state formation region PP is expressed as shown in FIG. 105 (b), and the resonance corresponding to FIG. 105 (a). An arrangement example of the resonance state forming lattice points 12A and the perturbation state forming lattice points 12P in the resonator region RP and the perturbation state forming region PP is expressed as shown in FIG. In the example shown in FIG. 105C, perturbation is applied in the y-axis direction to the resonance state forming lattice point 12A in the perturbation state forming region PP, and the perturbation state forming lattice points 12P1, 12P2, and 12P3 are formed. Is formed.

  Further, in the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the sizes of the resonator region RP and the perturbation state forming region PP of the two-dimensional photonic crystal layer 12 applied to the X-point oscillation are different. The NFP in this case is represented as shown in FIG. 106 (a), and the beam expansion region 30 from the perturbation state formation region PP is represented as shown in FIG. 106 (b) and corresponds to FIG. 106 (a). An arrangement example of the resonance state forming lattice points 12A and the perturbation state forming lattice points 12P in the resonator region RP and the perturbation state formation region PP is expressed as shown in FIG. In the example shown in FIG. 106C, perturbation is applied in the y-axis direction to the resonance state forming lattice point 12A in the perturbation state forming region PP, and the perturbation state forming lattice points 12P1, 12P2, and 12P3 are formed. Is formed.

  That is, in the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the resonator region RP and the perturbation state formation region PP can be designed separately, and only the arrangement of the perturbation state formation region PP is changed. By doing so, the beam emission angle and beam divergence angle of the surface emitting laser light can be variously changed while maintaining stable oscillation.

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the size of the resonator region RP in which the resonance state forming lattice point 12A is arranged is maintained, and the perturbation state forming lattice point 12P is maintained. By changing the arranged perturbation state formation region PP, the beam emission angle and beam divergence angle of the laser beam can be adjusted while maintaining stable oscillation.

(Disposition relation between perturbation state formation region PP and resonator region RP)
In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, a resonance state formation grating in the resonator region RP and the perturbation state formation region PP of the two-dimensional photonic crystal layer 12 applied to M-point oscillation An arrangement example of the point 12A and the perturbation state forming lattice point 12P is expressed as shown in FIG.

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, a perturbation state forming lattice point (12P1) is added to the resonance state forming lattice point 12A of the photonic crystal layer 12 in the y-axis direction. An example in which 12P2 and 12P3) are periodically arranged is expressed as shown in FIG.

  Further, an example in which perturbation state forming lattice points (12P1, 12P2, 12P3) are periodically arranged to the resonance state forming lattice points 12A of the photonic crystal layer 12 is shown in FIG. ).

  Further, a perturbation is applied to the resonance state forming lattice point 12A of the photonic crystal layer 12 in a direction inclined by about 45 degrees from the x-axis direction, and the perturbation state forming lattice points (12P1, 12P2, 12P3) are periodically arranged. This example is expressed as shown in FIG.

  Further, perturbation is applied to the resonance state forming lattice point 12A of the photonic crystal layer 12 in a direction inclined by about minus 45 degrees from the x-axis direction, and the perturbation state forming lattice points (12P1, 12P2, 12P3) are periodically arranged. This example is expressed as shown in FIG.

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the arrangement of the perturbation state forming lattice points 12P can be freely set as shown in FIGS. 108 (a) to 108 (d). .

(Beam shape control by perturbation state formation arrangement)
In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, when the sizes of the resonator region RP and the perturbation state formation region PP of the two-dimensional photonic crystal layer 12 applied to M-point oscillation are substantially equal NFP is expressed as shown in FIG. 109 (a), and the beam expansion region 30 from the perturbation state formation region PP is expressed as shown in FIG. 109 (b), and the resonance corresponding to FIG. 109 (a). An example of arrangement of the resonance state forming lattice points 12A and the perturbation state forming lattice points 12P in the resonator region RP and the perturbation state forming region PP is expressed as shown in FIG. 109 (c). In the example shown in FIG. 109 (c), perturbation is applied to the resonance state forming lattice point 12A in a direction inclined by about 45 degrees from the x-axis direction, and the perturbation state forming lattice points 12P1, 12P2,. 12P3 is formed.

  Further, in the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the sizes of the resonator region RP and the perturbation state forming region PP of the two-dimensional photonic crystal layer 12 applied to the M point oscillation are different. The NFP in this case is represented as shown in FIG. 110 (a), and the beam expansion region 30 from the perturbation state formation region PP is represented as shown in FIG. 110 (b) and corresponds to FIG. 110 (a). An arrangement example of the resonance state forming lattice points 12A and the perturbation state forming lattice points 12P in the resonator region RP and the perturbation state forming region PP is expressed as shown in FIG. In the example shown in FIG. 110 (c), a perturbation is applied to the resonance state forming lattice point 12A in the perturbation state formation region PP in a direction inclined by about 45 degrees from the x-axis direction. Grid points 12P1, 12P2, and 12P3 are formed.

  That is, in the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, it is possible to design the resonator and the perturbation state formation separately, and by changing only the arrangement of the perturbation state formation, While maintaining oscillation, the beam shape of the surface emitting laser light can be variously changed.

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the size of the resonator region RP in which the resonance state forming lattice point 12A is arranged is maintained, and the perturbation state forming lattice point 12P is maintained. By changing the arranged perturbation state formation region PP, the size and shape of the light emitting surface of the laser beam can be adjusted while maintaining stable oscillation.

(Other examples of beam generation)
In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, a relatively large circular perturbation state formation region PP in the resonator region RP of the two-dimensional photonic crystal layer 12 applied to M-point oscillation. The NFP in the case of having F is represented in the same manner as in FIG. 19A, and the FFP corresponding to FIG. 19A is represented in the same manner as in FIG. Here, the coupler region CP in FIG. 19A corresponds to the perturbation state formation region PP. The same applies hereinafter.

  Further, NFP in the case of having a relatively small circular perturbation state forming region PP in the resonator region RP is represented in the same manner as FIG. 20A, and the FFP corresponding to FIG. It is expressed in the same manner as (b).

  Further, NFP in the case of having a relatively small circular perturbation state formation region PP in the resonator region RP is represented in the same manner as FIG. 21A, and the FFP corresponding to FIG. It is expressed in the same manner as 21 (b).

  Further, NFP in the case of having a relatively large oval perturbation state forming region PP in the resonator region RP is expressed in the same manner as FIG. 22A, and the FFP corresponding to FIG. It is expressed in the same manner as 22 (b).

  Further, the NFP in the case where a plurality of relatively small circular perturbation state formation regions PP are arranged in the resonator region RP is represented in the same manner as FIG. 23A, and the FFP corresponding to FIG. It is expressed as shown in FIG.

  Further, NFP in the case of having two oval perturbation state formation regions PP orthogonal to each other in the resonator region RP is expressed as shown in FIG. 24A, and is shown in FIG. The corresponding FFP is represented as shown in FIG.

  Further, NFP in the case of having three oval perturbation state forming regions PP intersecting each other at 60 degrees in the resonator region RP is expressed as shown in FIG. The FFP corresponding to a) is expressed as shown in FIG.

  Further, NFP in the case of having two oval perturbation state formation regions PP intersecting each other at 120 degrees in the resonator region RP is expressed as shown in FIG. The FFP corresponding to a) is expressed as shown in FIG.

  Further, NFP in the case of having five oval perturbation state forming regions PP intersecting each other at 72 degrees in the resonator region RP is expressed as shown in FIG. The FFP corresponding to a) is expressed as shown in FIG.

  In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, as shown in FIGS. 19 to 27, the oscillation region size is maintained in the oscillation at the M-point band edge in the photonic band structure. The size and shape of the light emitting surface of the laser beam can be adjusted by relatively changing the size of the perturbation state formation region PP. As examples of the size of the NFP, various sizes such as several tens of μm square, several hundreds of μm square, and 1 mm square can be formed, and the same applies to the corresponding FFP.

In the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment, the beam divergence angle θ ₀ and the shape of the laser beam are determined by the size and shape of the light emitting surface of the laser beam. The spread angle and shape can be controlled. As long as the periodic structure for optical amplification is maintained, oscillation is possible even if the size and shape of the perturbation state formation region PP is changed.

Since the laser beam divergence angle θ ₀ and shape are determined by the size and shape of the light emitting surface, for example, when the laser beam divergence angle θ _{0 is} to be increased, the size of the optical amplification resonator region RP is As it is, the size of the perturbation state formation region PP may be made relatively small. In addition, when the shape of the laser beam is desired to be rectangular, the perturbation state forming region PP may be rectangular.

  In particular, since the two-dimensional photonic crystal surface emitting laser according to the tenth embodiment can control the beam emission angle, beam divergence angle, and shape of the laser beam, as shown in FIGS. Various shapes can be used for lens-free markers.

[Eleventh embodiment]
(Two-dimensional cell array)
In the two-dimensional photonic crystal surface emitting laser according to the eleventh embodiment, a configuration example in which a two-dimensional cell array is used to increase the output is expressed as shown in FIG. That is, the cells 32 of the two-dimensional photonic crystal surface emitting lasers according to the ninth to tenth embodiments may be two-dimensionally arranged on the substrate 100 to form a two-dimensional cell array. For example, in an example in which 21 cells 32 are two-dimensionally arranged to form a two-dimensional cell array, a high-power two-dimensional photonic crystal surface emitting laser with a current value of about 50 A and a high output of 35 W can be obtained by pulse driving at 1 kHz and 50 nsec. It has been.

  In the example shown in FIG. 111, each cell 32 may be provided with cells having different area ratios between the perturbation state formation region PP and the resonator region RP. A plurality of cells 32 having different area ratios between the perturbation state formation region PP and the resonator region RP are arranged on the same substrate 100 and selectively driven, whereby the beam divergence angle and shape of the laser beam can be controlled. A high-power multifunction two-dimensional photonic crystal surface emitting laser array can be provided.

In the two-dimensional photonic crystal surface emitting laser according to the eleventh embodiment, the basic pattern T ₀ of the resonance state forming lattice point 12A is disposed on the two-dimensional photonic crystal layer 12 on the first cladding layer, and the rectangular shape is rectangular. A two-dimensional cell array configuration example in which the perturbation patterns T ₁ , T ₂ , T _3, and T ₄ of the shape perturbation state forming regions PP1, PP2, PP3, and PP4 are arranged is expressed as shown in FIG. . Further, the basic pattern T ₀ of the resonance state forming lattice point 12A is arranged on the two-dimensional photonic crystal layer 12 on the first cladding layer, and the perturbation pattern T of the hexagonal perturbation state forming regions PP1, PP2, PP3. _A configuration example of a two-dimensional cell array in which ₁ · T ₂ · T ₃ is arranged is expressed as shown in FIG.

  In the example shown in FIGS. 112 (a) and 112 (b), a high-output multifunctional two-dimensional capable of controlling the beam emission angle, beam divergence angle, and shape of the laser beam by arranging a plurality of perturbation patterns. A photonic crystal surface emitting laser array can be provided.

  In the two-dimensional photonic crystal surface emitting laser according to the eleventh embodiment, a two-dimensional structure in which the configuration shown in FIG. 112B is arranged on a plurality of chips CH1, CH2, CH3, and CH4 on the same substrate 100. A cell array configuration example is represented as shown in FIG.

In the example shown in FIG. 113, on the same substrate 100, respectively disposing a plurality of chips CH1 · CH2 · CH3 · CH4 having a plurality of perturbation patterns _{T 1 · T 2 · T 3} , to selectively drive Thus, it is possible to provide a high-output multifunctional two-dimensional photonic crystal surface emitting laser array capable of controlling the beam divergence angle and shape of the laser beam.

  In the two-dimensional photonic crystal surface emitting laser according to the eleventh embodiment, a plurality of chips CH1, CH2, CH3, and CH4 having different FFPs (FFP1, FFP2, FFP3, and FFP4) are formed on the same substrate 100. An example of a configuration in which the two-dimensional cell array is arranged is expressed as shown in FIG.

  In the example shown in FIG. 114, chips CH1, CH2, CH3, and CH4 each having different FFP1, FFP2, FFP3, and FFP4 are arranged on the same substrate 100, and selectively driven, so that the beam of the laser beam is obtained. A high-output multifunctional two-dimensional photonic crystal surface emitting laser array capable of controlling the spread angle and shape can be provided.

  As described above, according to the present invention, a two-dimensional photonic crystal surface emitting laser capable of controlling the beam emission angle, beam divergence angle, and shape of a laser beam while maintaining stable oscillation with a simple structure. Can be provided.

[Other embodiments]
As described above, the present invention has been described with reference to the first to eleventh embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  The two-dimensional photonic crystal surface emitting laser of the present invention can be used for all surface emitting LD elements. For example, a light source for AF (autofocus) pattern, a distance measuring light source such as a distance sensor, a laser processing light source, It can be applied to a wide range of application fields such as light sources applicable to medical applications, optical tweezers, light sources for next-generation optical disc pickups, DVDs, BDs, and inter-chip communication devices.

  If the scanning function is provided, the light source for laser beam printer, mobile laser display, light source for inter-chip optical communication equipment, capsule endoscope with built-in laser, capsule laser knife with built-in laser, inter-vehicle distance measuring laser, laser pointer laser The present invention can be applied to application fields such as a scan display and a barcode scanner.

10 ... 1st clad layer (p clad layer)
12 ... Photonic crystal layer 12 ₁ ... 1st photonic crystal layer (photonic crystal layer for standing wave formation)
12 ₂ ... 2nd photonic crystal layer (photonic crystal layer for light emission)
12A: Resonator lattice points (resonator holes, resonance state forming lattice points)
12C ... Coupler grid points (holes for couplers)
12P, 12P ₁ · 12P ₂ · 12P ₃ ... Perturbed state forming lattice points 13... Carrier block layer 14... Active layer (MQW)
16 ... 2nd clad layer (n clad layer)
18 ... contact layer 20 ... window layer 22 ... upper electrode 24,100 ... substrate 26 ... lower electrode 30, 30 _1, 30 _2, 30 ₃ ... beam spread area 32 ... cell lambda ... medium wavelength P, Q, R ... Band speed edge region c ... light _{a, a 1, a 2,} a x, a y ... lattice constant c / a ... units of normalized frequency _{CP, CP 1, CP 2,} CP 3 ... coupler regions a _1, a ₂ , A ₃ ... coupler region width (perturbation state formation region width)
RP: Resonator regions PP, PP ₁ , PP ₂ , PP ₃ ... Perturbation state formation regions d, D1, D2, D3 ... Hole diameters h, H1, H2, H3 ... Hole depths n, n1, n2, n3 ... Refraction Factors θ ₀ , θ ₃ , θ _a , θ _b , θ _c ... Beam divergence angles θ ₁ , θ ₂ , θ ₃ ... Beam divergence angles θ, θ ₁₁ , θ ₂₂ ... Beam emission angles θ _d ... Beam emission in the medium Angle θ _air ... Beam emission angle in the atmosphere r ... Aspect ratio (a ₁ / a ₂ )
k _f ... fundamental wave number (wave vector)
λ _PC ... center wavelength λ _air ... center wavelength in _air n _eff ... effective refractive index k _d ... diffraction vector s ... perturbation coefficient FFP ... far-field pattern (far field pattern)
NFP ... Near-field image (near field pattern)
hν _L ... surface emitting laser light hν _R ... intracavity laser light

Claims (43)

A photonic crystal layer;
A resonant state forming lattice point that is periodically arranged in the photonic crystal layer and diffracts a light wave at a band edge of the photonic band structure of the photonic crystal layer in a plane of the photonic crystal layer. ,
A perturbation for diffracting the light wave in a direction perpendicular to the surface of the photonic crystal layer is applied to the resonance state forming lattice point ,
2. A two-dimensional photonic crystal surface emitting laser , wherein a plurality of perturbations are applied to the resonance state forming lattice points .   2. The two-dimensional photonic crystal surface emitting laser according to claim 1, wherein the perturbation applied to the resonance state forming lattice point is periodic modulation.   The two-dimensional photonic crystal surface emitting laser according to claim 2, wherein the periodic modulation is refractive index modulation.   The two-dimensional photonic crystal surface emitting laser according to claim 2, wherein the periodic modulation is a hole size modulation.   The two-dimensional photonic crystal surface emitting laser according to claim 2, wherein the periodic modulation is hole depth modulation.   The two-dimensional photonic crystal surface emitting laser according to claim 2, wherein the periodic modulation is hole size modulation and hole depth modulation.   The said resonance state formation lattice point is arrange | positioned in any of a square lattice, a rectangular lattice, a face center rectangular lattice, or a triangular lattice, The any one of Claims 1-6 characterized by the above-mentioned. Two-dimensional photonic crystal surface emitting laser.   The resonance state forming lattice points are arranged in a square lattice or a rectangular lattice, and light waves at the Γ point, the X point, or the M point in the photonic band structure of the photonic crystal layer are transmitted to the surface of the photonic crystal layer. The two-dimensional photonic crystal surface emitting laser according to claim 1, wherein the two-dimensional photonic crystal surface emitting laser can be diffracted in a vertical direction.   The resonance state forming lattice points are arranged in a face-centered rectangular lattice or a triangular lattice, and light waves at the Γ point, the X point, or the J point in the photonic band structure of the photonic crystal layer are transmitted to the photonic crystal layer. The two-dimensional photonic crystal surface emitting laser according to claim 1, wherein the two-dimensional photonic crystal surface emitting laser can be diffracted in a direction perpendicular to the surface. A substrate,
A first cladding layer disposed on the substrate;
A second cladding layer disposed on the first cladding layer;
The two-dimensional photonic crystal surface emitting laser according to any one of claims 1 to 9, further comprising: an active layer sandwiched between the first cladding layer and the second cladding layer.   11. The photonic crystal layer according to claim 10, wherein the photonic crystal layer is disposed adjacent to the active layer in a direction perpendicular to the surface of the active layer between the first cladding layer and the second cladding layer. The two-dimensional photonic crystal surface emitting laser described.   The two-dimensional photonic crystal surface emitting laser according to claim 10, wherein the photonic crystal layer is disposed between the first cladding layer and the active layer.   The two-dimensional photonic crystal surface emitting laser according to claim 10, wherein the photonic crystal layer is disposed between the second cladding layer and the active layer. The two-dimensional photonic crystal surface emitting laser according to any one of claims 1 to 13, wherein the plurality of perturbations are applied in an arbitrary direction. The two-dimensional photonic crystal surface emitting laser according to any one of claims 1 to 14, wherein the plurality of perturbations are added by superposition. A photonic crystal layer;
Resonance state forming lattice points that are periodically arranged in the photonic crystal layer and diffract light waves at the band edges of the photonic band structure of the photonic crystal layer in the plane of the photonic crystal layer;
Periodically disposed in the photonic crystal layer, diffracts the light wave at the band edge of the photonic band structure of the photonic crystal layer in the plane of the photonic crystal layer and is perpendicular to the plane of the photonic crystal layer. Lattice points for perturbation state formation diffracted in the direction
With
The perturbation state forming lattice point is formed by adding a perturbation for diffracting the light wave in a direction perpendicular to the plane of the photonic crystal layer to a part of the resonance state forming lattice point,
A two-dimensional photonic crystal surface emitting laser, wherein a plurality of perturbations are applied to the perturbation state forming lattice points. The two-dimensional photonic crystal surface emitting laser according to claim 16, wherein the perturbation applied to the perturbation state forming lattice point is periodic modulation. The two-dimensional photonic crystal surface emitting laser according to claim 17, wherein the periodic modulation is refractive index modulation. The two-dimensional photonic crystal surface emitting laser according to claim 17, wherein the periodic modulation is a hole size modulation. The two-dimensional photonic crystal surface emitting laser according to claim 17, wherein the periodic modulation is hole depth modulation. 18. The two-dimensional photonic crystal surface emitting laser according to claim 17, wherein the periodic modulation is hole size modulation and hole depth modulation. A substrate,
A first cladding layer disposed on the substrate;
A second cladding layer disposed on the first cladding layer;
An active layer sandwiched between the first cladding layer and the second cladding layer;
The two-dimensional photonic crystal surface emitting laser according to any one of claims 16 to 21, wherein the two-dimensional photonic crystal surface emitting laser is provided. 23. The photonic crystal layer according to claim 22, wherein the photonic crystal layer is disposed between the first cladding layer and the second cladding layer and adjacent to the active layer in a direction perpendicular to the surface of the active layer. The two-dimensional photonic crystal surface emitting laser described. The two-dimensional photonic crystal surface emitting laser according to claim 22, wherein the photonic crystal layer is disposed between the first cladding layer and the active layer. The two-dimensional photonic crystal surface emitting laser according to claim 22, wherein the photonic crystal layer is disposed between the second cladding layer and the active layer. 17. The resonance state forming lattice points and the perturbation state forming lattice points are arranged in any of a square lattice, a rectangular lattice, a face-centered rectangular lattice, or a triangular lattice. 26. The two-dimensional photonic crystal surface emitting laser according to any one of 25. The resonance state forming lattice points and the perturbation state forming lattice points are arranged in a square lattice or a rectangular lattice, and light waves at the Γ point, the X point, or the M point in the photonic band structure of the photonic crystal layer. The two-dimensional photonic crystal surface emitting laser according to any one of claims 16 to 25, wherein the two-dimensional photonic crystal surface emitting laser can be diffracted in a direction perpendicular to the surface of the photonic crystal layer. The resonance state forming lattice point and the perturbation state forming lattice point are arranged in a face-centered rectangular lattice or a triangular lattice, and the Γ point, the X point, or the J point in the photonic band structure of the photonic crystal layer 26. The two-dimensional photonic crystal surface emitting laser according to any one of claims 16 to 25, wherein the light wave at can be diffracted in a direction perpendicular to the surface of the photonic crystal layer. 29. The two-dimensional photonic crystal surface emitting laser according to claim 16, wherein the plurality of perturbations are applied in an arbitrary direction. 30. The two-dimensional photonic crystal surface emitting laser according to claim 16, wherein the plurality of perturbations are applied by superposition. By changing the perturbation state formation region where the perturbation state formation lattice points are arranged while maintaining the size of the resonator region where the resonance state formation lattice points are arranged, the size of the light emitting surface of the laser beam is changed. The two-dimensional photonic crystal surface emitting laser according to any one of claims 16 to 30, wherein the height and shape are adjusted. The resonance state forming lattice points that diffract light waves at the M-point band edge in the photonic band structure of the photonic crystal layer are arranged in a square lattice,
The perturbation state forming lattice points are arranged in a face-centered square lattice having a lattice constant twice as large as the lattice constant of the square lattice, and the diagonal pitch of the perturbation state forming lattice points is the photonic crystal The two-dimensional photonic crystal surface emitting laser according to any one of claims 16 to 25, wherein the two-dimensional photonic crystal surface emitting laser is equal to a wavelength in the medium of the layer. The resonance state forming lattice point that diffracts the light wave at the X-point band edge in the photonic band structure of the photonic crystal layer is disposed in a first square lattice,
The perturbation state forming lattice points are arranged in a second square lattice having a lattice constant twice as large as the lattice constant of the first square lattice, and the lattice constant of the perturbation state forming lattice points is the photonic crystal The two-dimensional photonic crystal surface emitting laser according to any one of claims 16 to 25, wherein the two-dimensional photonic crystal surface emitting laser is equal to a wavelength in the medium of the layer. The resonance state forming lattice point that diffracts the light wave at the X-point band edge in the photonic band structure of the photonic crystal layer is disposed in a first triangular lattice,
The perturbation state forming lattice points are arranged in a second triangular lattice having a pitch twice the pitch of the first triangular lattice, and the height of the second triangular lattice in plan view is the height of the photonic crystal layer. The two-dimensional photonic crystal surface emitting laser according to any one of claims 16 to 25, wherein the two-dimensional photonic crystal surface emitting laser is equal to an in-medium wavelength. The resonance state forming lattice point that diffracts the light wave at the J-point band edge in the photonic band structure of the photonic crystal layer is disposed in a first triangular lattice,
The perturbation state forming lattice points are arranged in a face-centered triangular lattice having a pitch three times the pitch of the first triangular lattice, and one side of the face-centered triangular lattice has an in-medium wavelength of the photonic crystal layer. The two-dimensional photonic crystal surface emitting laser according to any one of claims 16 to 25, wherein the two-dimensional photonic crystal surface emitting laser is equal to two times. The resonance state forming lattice point that diffracts the light wave at the X-point band edge in the photonic band structure of the photonic crystal layer has a lattice constant a ₁ And a ₂ Arranged in a first rectangular lattice having
The perturbation state forming lattice points are arranged in a second rectangular lattice different from the first rectangular lattice, and the lattice constant of the second rectangular lattice is the same as that of the first rectangular lattice. Lattice constant a ₁ And a ₂ The aspect ratio defined by ₁ / A ₂ The two-dimensional photonic crystal surface emitting laser according to any one of claims 16 to 25, wherein (r ≠ 1) is equal to r times the wavelength in the medium and equal to the wavelength in the medium. The resonance state forming lattice point that diffracts the light wave at the X-point band edge in the photonic band structure of the photonic crystal layer has a lattice constant a ₁ And a ₂ Arranged in a face-centered rectangular lattice having
The perturbation state forming lattice points are arranged in a rectangular lattice, and the lattice constant of the rectangular lattice is the lattice constant a of the face-centered rectangular lattice. ₁ And a ₂ The aspect ratio defined by ₁ / A ₂ The two-dimensional photonic crystal surface emitting laser according to any one of claims 16 to 25, wherein (r ≠ 1) is equal to r times the wavelength in the medium and equal to the wavelength in the medium. A photonic crystal layer;
A rectangular lattice disposed in the photonic crystal layer and diffracts the light wave at the X-point band edge in the photonic band structure of the photonic crystal layer in the plane of the photonic crystal layer and in the direction perpendicular to the plane. Resonance state forming lattice points of
With
A perturbation for diffracting the light wave in the direction perpendicular to the plane of the photonic crystal layer is applied to the resonance state forming lattice point, and the lattice constant of the rectangular lattice is defined as a. ₁ And a ₂ Then, one side a of the rectangular lattice ₂ Is a two-dimensional photonic crystal surface emitting laser characterized in that is equal to ½ of the wavelength in the medium. A photonic crystal layer;
A lattice point for forming a resonance state of a rectangular lattice disposed in the photonic crystal layer and diffracting a light wave at the X-point band edge in the photonic crystal layer of the photonic crystal layer in the plane of the photonic crystal layer When,
A lattice point for forming a perturbation state for diffracting a light wave at an X-point band edge in the photonic band structure of the photonic crystal layer in a direction perpendicular to the plane of the photonic crystal layer;
The perturbation state forming lattice point is formed by adding a perturbation for diffracting the light wave in a direction perpendicular to the plane of the photonic crystal layer to a part of the resonance state forming lattice point, and The lattice constant of the rectangular lattice is a ₁ And a ₂ Then, one side a of the rectangular lattice ₂ Is a two-dimensional photonic crystal surface emitting laser characterized in that is equal to ½ of the wavelength in the medium. By changing the perturbation state formation region where the perturbation state formation lattice point is arranged while maintaining the size of the resonator region where the resonance state formation lattice point is arranged, the beam divergence angle of the laser beam is changed. 40. The two-dimensional photonic crystal surface emitting laser according to claim 39, which is controlled. A photonic crystal layer;
Resonant state formation of a first rectangular lattice disposed in the photonic crystal layer and diffracting a light wave at the X-point band end in the photonic band structure of the photonic crystal layer in the plane of the photonic crystal layer Grid points for
A lattice point for forming a perturbation state for diffracting a light wave at an X-point band edge in the photonic band structure of the photonic crystal layer in a direction perpendicular to the plane of the photonic crystal layer;
The perturbation state forming lattice point is formed by adding a perturbation for diffracting the light wave in a direction perpendicular to the plane of the photonic crystal layer to a part of the resonance state forming lattice point, and The perturbation state forming lattice points are arranged in a second rectangular lattice different from the first rectangular lattice, and lattice constants in the x and y directions of the second rectangular lattice are Lattice constant a in the x-direction and y-direction of one rectangular lattice ₁ And a ₂ Against a ₁ And the wavelength λ in the medium (= 2a ₂ A two-dimensional photonic crystal surface emitting laser, characterized in that A photonic crystal layer;
A lattice point for forming a resonance state of a rhomboid lattice that is disposed in the photonic crystal layer and diffracts a light wave at the X-point band end in the photonic band structure of the photonic crystal layer in the plane of the photonic crystal layer; ,
A lattice point for forming a perturbation state for diffracting a light wave at an X-point band edge in the photonic band structure of the photonic crystal layer in a direction perpendicular to the plane of the photonic crystal layer;
The perturbation state forming lattice point is formed by adding a perturbation for diffracting the light wave in a direction perpendicular to the plane of the photonic crystal layer to a part of the resonance state forming lattice point, and The lattice points for forming the perturbation state are arranged in a rectangular lattice, and the lattice constant of the rectangular lattice is the lattice constant a of the rhomboid lattice. ₁ And a ₂ Against a ₁ And a two-dimensional photonic crystal surface emitting laser characterized by being equal to the wavelength λ in the medium. 43. A two-dimensional photonic crystal surface emitting laser, wherein the cells of the two-dimensional photonic crystal surface emitting laser according to any one of claims 1 to 42 are two-dimensionally arranged to form a two-dimensional cell array.